Most of this information was gathered from 2 other websites. 
Reasons for Ghosts

GHOSTS – Are human spirits that have not crossed over into their rightful place and are dwelling in-between the two realms, the physical world & spirit world.

REASONS FOR GHOST:

They died as a result of a traumatic event such as; murder, car accident, etc.

They may have died suddenly and not realize they have passed.

They may have been confused at the time of death, by a mental state of mind.

They are searching for someone or something they have lost in their lifetime.

The living love-ones are so emotionally distraught, they can’t let go of the person that passed.

The spirit is emotionally connected to their love-ones.

The spirit has an emotional connection to a place or item.

They have unfinished business.

They cannot rest due to an injustice done to them.

Fear of the other side, the unknown.

The fear of the judgment they will face on the other side.

A lack of faith.

Different types of Spirits
Ghost

They are human spirits that have not crossed over to their rightful place and are dwelling in between the two realms, the physical and the spirit.

Family Ghost

Ghosts which are connected to a particular family. They may have unresolved issues with someone in the family, it could be fairly current or go back to your ancestors.

Full Body Apparition

A ghost or spirit is seen in a solid form.

Spirit

The incorporeal part of humans, such as the mind or soul.  It can also be a supernatural, incorporeal being having a particular character.

Non-human Spirits


Nonhuman spirits are exactly what the name implies. These spirits are not human and have never been human. Nonhuman spirits are able to manifest themselves in any form they choose. Not all nonhuman spirits are malicious.

Entity

A being or existence that exists as distinct, independent, or self-contained being.

Non-physical Entity

An entity that lacks a physical or material body or material or physical characteristics. In some religions they are believed to be deties, devas, gods or goddess, etc. They belong to a supra-physical plane of existence.

Elementals

Nature spirits. Their essence is unique and specific to one of the four elements of the physical universe: air, fire, water, and earth. A fifth element, Ether, is the element of spirit. It  is the realm of angelic beings and other non corporeal, or non physical beings.

Non-corporeal Being


Composed of various forms of intelligent energy, these beings absorb and use energy from their environment.  Some feed off of human energy.

Parasitic Entity

An intelligent energetic being that manipulates and attaches itself to a human host, much like a leech.

Demons

Malevolent non-human entity that torments humans.

Graveyard Specters

Also known as shells or shades, these apparitions are believed to be ethereal remnants left after a person’s death. They are commonly found in graveyards days or weeks after a burial. They are seen as dark or gray shadowy forms.

Shadow People

These are spirits that appear in a human form. A shadow person may simply be a ghost that does not have the energy to fully manifest itself. It may also be a spirit carrying a strong negative emotion, such as anger, sadness, hatred, etc. This often causes their energy to be darkened. There are also reports of shadow animals.

Shadow Creatures

These beings are different from ghosts; they are not human entities. They usually appear as shapeless dark masses. They have no human features, though they are sometimes seen as hooded, cloaked figures, or wearing a hat.

Some people say they seem to be made up of dark smoke or dark steam. Some are seen as child-sized dark humanoids while others are 7-8 ft tall. People who encounter them have a feeling of dread.
Different Types ofHauntings 


The Interactive Personality

The most common of all ghosts spotted is usually of a deceased person, someone you know, a family member or perhaps even a historical figure. These ghosts can be friendly or not – but often show themselves to others in a variety of ways. They can become visible; they can speak or make noises, touch you or even emit an odor like perfume or cigar smoke, etc, to let you know they are there. Experts say that this type of ghost retains its former personality of when they were alive and can feel emotions. And often, they are visiting you to comfort you or let you know something important. So if you happen to see a lost loved one, chances are they are there because they feel you want or need to see them.

Intelligent Haunting 

Perhaps the most widely accepted kind of ghostly activity. Here the spirit or entity involved is an “intelligent” presence in a haunted location. It is there because of a connection to the site, or to the people, in the location. This ghost is best (and most simply) described as the personality of a person who once lived and has stayed behind, instead of crossing over to the other side. In this type of haunting, you are dealing with an "intelligent" presence that can communicate with you, and interact with you in a seemingly "intelligent" way. An intelligent ghost haunting is best described as a responsive usually human entity with whom you have interactive intelligent communication. This type entity is seemingly the personality of a person who once lived, and who is either "trapped" in our world or in between ours and another realm or has already moved onto the next plane and can now freely travel back and forth between our realm and theirs, and or presumably elsewhere.  Intelligent ghosts are not "evil" or "dangerous" as some people would have you believe. "Intelligent"ghosts are simply human personalities, and if the spirit was a kind and caring person in life, the spirit will most likely be the same way in death. Likewise, angry and mean people will usually keep those same negative character traits as spirits. An intelligent haunting/ghost will likely seek to get the attention of living people. To get attention, the ghost may try turning things on and off, hiding objects, moving things, make noises, and other type of annoying or nuisance behavior.  

The ghost/spirit may be looking for assistance to pass over or for assistance to accomplish a certain task, or may just be letting you know they are around with no other intent or need. Occasionally the human entity is stuck in a death state and does not know they are dead and is simply continuing with life as unusual. The ghost has somehow been trapped between two planes of existence and is unable to move on. However, more times than not though, the entities we comes across are able to move about freely, coming and going as they choose.

The key factor in an intelligent haunting is that the ghost can interact with you (communication—it responds and notices human beings).  If the ghost does not notice you or other human beings, and cannot interact or communicate with you, it's not an intelligent haunting.


Residual Haunting

Is believed to be caused by traumatic past events that leave an imprint on the environment. These imprints replay over and over. No spirit or ghost is involved, it’s just like watching a movie.  There is no interaction with the living.

The theory in this sort of haunting is that the energy expended during repetitive or traumatic events is absorbed and stored in the electromagnetic field at the site. Over time the energy builds up, when the energy can no longer be contained it is discharged, showing a replay of the traumatic event that once took place. Once the event is played out then the cycle begins again.

Some suggest that atmospheric conditions, such as storms, may initiate the playback. There is also a quantum physics-related theory that explains the energy as particles of light that are dormant until they are stimulated by an outside variable under the proper conditions. Energy from a traumatic event is trapped in an object at the location.
When environmental circumstances are correct, the energy replays a certain aspect of the traumatic event.
This type of activity is either present in location already or will occur when someone buys an Antique or brings an object into home that the energy is connected to. 

Identification:

– The activity repeats itself. Like a Tape recorder playing itself over and over again. It always seems to be the same type of activity. Always follows the same pattern. Walking just one certain path at the same time each day, month, year, Etc

– The entity does not acknowledge its surroundings. If you decide to move a doorway and cover an old doorway a Residual entity will not acknowledge the change. It will follow the same path it always has.
In return walking directly through the wall where the door once stood.

– Nothing actually moves. You may hear sounds of something moving, But nothing actually will move.

Removal:

– Can be removed if object containing the energy is found and removed from the location.


Reoccurring Haunting

This type of haunting appears very similar to a residual haunting, except that there is some kind of intelligence involved. In this case, the activity is caused by a spirit trapped between realms, reliving a moment in the past, over and over until the pattern is disrupted.

Historical Haunting

Ghosts can be seen in more than one location, going about their business. Typically they are dressed in period clothing and often appear solid. They may interact with the living, but they believe they are living in their own time.

Portal Haunting

Portals are a link, or doorway, between our physical world and the spiritual world. Spirits can enter into our world through a portal. Portals can be created through a ritual or caused by a natural energy source coming from the earth, such as ley lines.

Poltergeist

This is a spirit, usually mischievous and occasionally malevolent, which can manifest its presence by making noises, moving objects, and assaulting people and animals.

The term “poltergeist” comes from the German poltern, “to knock,” and geist, “spirit.”

Some cases of poltergeists remain unexplained and may involve actual spirits. In other cases the phenomena may be produced by subconscious psychokinesis on the part of an individual.

The most common types of poltergeist activities are: rains of stones, dirt, and other small objects; loud noises and shrieks; objects, including large pieces of furniture, being moved or thrown; and vile smells.

It seems that poltergeists have adapted to the development of technology. They are suspected to have caused interference in telephones and electronic equipment, and turning lights and appliances on and off. Some poltergeists are said to pinch, bite, hit, and sexually assault the living.

Generally poltergeist activity starts and stops abruptly. The activity almost always occurs at night and in the presence of a certain person. Typically this is the “agent,” an individual who seems to serve as a focus or magnet for the activity.

Malevolent (aka Demonic) Haunting



This type of haunting is usually caused by a malevolent, nonhuman entity or demon. Although human spirits can cause some of the same activity, it is rare.

They often start out with subtle and relatively simple activity, which then quickly increases in intensity. They can be very dramatic and violent in nature. There will be poltergeist activity (see description above), as well as vicious attacks on the living that result in psychological and physical harm.

Sometimes the attacks are sexual in nature, which can also include very vivid dreams of sexual acts. It will weaken its victim’s psychological and emotional state, which will influence his or her behavior.

The entity will wear it’s victim down until it can gain full control of them through possession. If a living person is possessed, they can remain under the oppression or possession even when their bodies die. Furthermore a human entity (one without a body any longer) can come under attack from a demon or negative entity (even a possessed human entity) while on the other side and become oppressed or possessed even if they weren't while living. Demonic Haunting

Demon hauntings usually start in a subtle way. Behaviors are typically the same behaviors displayed by a poltergeist, but more extreme. It's common for one or several entities to exist in one location with a strong evil presence seemingly controlling the others and not allowing them to cross over.

It is believed that demons hate humans and think them very lowly and stupid. Demons should never be challenged. Most demonic entities like a challenge and are master of trickery and incredibly conniving; they may have you believing they are good spirits or may appear to have gone away, only to confront you again at the least expected and most vulnerable moment.

A demon is considered to be a powerful, supernatural being that is generally malevolent (wishing or appearing to wish evil to others) in character. The word demon comes from the Greek word daimon, which means a divine or semi-divine power that determined a person's fate.

Demons are evil, supernatural beings of intelligence, wit, and immense power. They have the power to invade our homes, attach themselves to objects, and inflict torture both mentally and emotionally by attacking or even possessing the human body.

Demons have the ability to morph into any shape they want. They can change from a human form to an inhuman form before your very eyes. They are neither male nor female, but will change to whatever meets their need at the time. Demons are commonly seen as black masses standing in doorways or in the corner of the room.

Shadow People


We still really don't know what all shadow people are, but they do need a category all their own. There are several different types or forms of shadow people, from Hatman to a plain ordinary human ghost who simply cannot manifest into full bodied apparition and seem to appear simply as shadow people.

At first, they appear only out of the corner of your eye, furtively darting out of view when you turn to look straight at them, but are now gone.  Did you really see them? Shaking the image out of your head, you assume that it was some peculiar anomaly of your eyesight (which is possible), however the feeling still lingers. Occasionally, you see the shadow directly in front of you: face to face, blacker than black, darker than dark, like a void that has punched a hole into the fabric of night itself.
   
Sometimes it appears as the mere silhouette of a person, and it may lack any specific characteristics of gender.  However, in no way does the description end there.  There are “hatted” shadow beings, hooded shadows, cloaked ones, and solid or wispy, smoky types.  Some are seen only from the waist up.  Others clearly have legs that are seen fleeing from their observers.   They dart into corners, through walls, into closets, or behind television sets, bushes, and buildings.  Sometimes they simply fade into the dark recesses of the night.  Lacking in the description is one common denominator unifying the many different types of shadow people that enter our world, except that they are “intensely dark.”  But even then, there are exceptions. 

The personalities and intentions of shadow people are just as varied. One can only hope that serious research into this paranormal genre will paint a clearer understanding of the nature and make-up of these dark mysterious shadows. In the meantime, although their existence isn’t in question, the nature of their being is.

Parasitic Entities and Spirits

To begin understanding the nature of parasite spirits, those that seem to attach themselves to and draw energy from individuals, consider the nature of spirits in general. First, spirits aren’t from around here: they are either tourists or invited guest that didn’t know when to go home. Either way, the material, physical universe is not their natural habitat.

Spirits, whether invited (summoned) or attracted to a place, a thing, or a living person, need energy to manifest in the physical world. Summoners, alone or in groups, raise the level of energy using it to attract and manifest a spirit. Those tied to a location are usually attracted by any event causing a sudden increase in emotions or a sharping of the focus of attention, either of which increases the energy level. The key element is the energy state of living things, it doesn’t have to be human, but must be alive.

With volumes of books on the subject, how spirits manifest is covered pretty extensively. Generally speaking, when summoned or attracted by events, spirits are bound or anchored by the conditions that bring them here. Our concern, are those spirits that have become unanchored. Summoned spirits can be unbound by accident or, in some cases, by design of the summoners. Location spirits can be unbound by the alteration or destruction of their domain.

Most will simply return home when the energy dissipates. Some will find other places with similar energies to move to. Of those that stay many will drift around collecting enough energy to sustain themselves, rarely interacting with the physical world around them to any noticeable degree. Usually there is no harmful intent and they pretty much leave us alone. 

Parasites are like junkies; they’re hooked on the taste of energy. They are gluttons gorging themselves at our expense. The more they feed, the more they need.

Most siphon off your energy in a particular way. Whether by choice or by limitation, spirits tap specific energy centers (Chakra) or emotional centers. Over time, by manipulating the way energy flows through you, or by tapping strong emotional responses, a parasite can drain you dry. Given enough time a parasite’s drain can lead to physical illness or an emotional crisis just like physical parasites do.

Once they learn their way around spirits can manipulate your energy to reinforce the mode of energy they prefer. How you feel influences your decisions; the results of your choices influence how you feel. A well known pair, the Succubus and her brother the Incubus, live off sexual energy. To increase the harvest they try to keep lust high on the host’s priority list. It’s usually a lot more subtle than that, but you get the idea. You can become fixated on what the spirit needs your energy type and level to be and as soon as it gets its fill, suddenly you’re drained. It can look a lot like a manic/depressive cycle, but it isn’t and it happens over a relatively short space of time.

That influence is what makes a parasite spirit really dangerous. It is also what makes them vulnerable. Once the spirit and the influence are identified removing them entails working around the influence to change the energy flow. It gets more difficult the longer the spirit has been with the host. Essentially, however, the key to ridding yourself of one of these nasties is an awareness of the spirit’s interest, and a willingness to push it off, repeatedly in some cases.
Protect Yourself Against Attacks

When an entity attacks a person it is called a psychic attack. A psychic attack is a manipulation of the energetic body known as the aura.

To be under psychic attack means that a negative energy is focused on penetrating your aura to cause harm. Once the aura is penetrated the negative energy can cause physical and spiritual harm.

Psychic attacks can come from living people that have ill intentions towards you, negative ghost and spirits, dark entities and demons.

Note: Below we have a list of symptoms of what may experience when under psychic attack, but keep in mind that they can also be psychiatric or psychological changes; therefore, you must be wary when you look at these as symptoms.

1. A feeling of being watched
2. A feeling someone touch when no one is present
3. Hearing disembody voices
4. Sudden changes in personality and behavior for no reason
5. A loss of self-confidence
6. Irrational fear, anger or sorrow
7. Sudden depression without an apparent reason
8. Sudden and irrational difficulties with relationships
9. Feeling you have been cut or scratched, when no one is there
10. Icy cold sensation on your body.
11. Feeling drained or a sudden loss of energy
12. Fatigue for no reason
13. Memory and/or time loss
14. Unable to think clearly or make logical decisions
15. Frequent or recurring nightmares
16. Imagining monsters, animals or frightening shadows
17. Visions or hallucinations that are disturbing
18. Strange recurring accidents that can seem like bad luck
20. Sudden illnesses that elude diagnosis and cannot be explained
21. A negative obsessive thought, desire or fetish that won’t go away
22. A discomfort or fear in a specific room or area in your home

Our aura is our natural psychic protection. Aura parameters such as colors, size, shape, evenness, and uniformity change dynamically over time in response to the total environment. It is affected by such factors as daily stress, psychological bombardment, other people’s intentions and desires toward us, jealousy, induced fear, threats, hatred, and noise which can cause the aura to shrink or create wear and tear, repressed or negative emotions, spiritual warfare, alcohol and/or drug abuse.

It’s difficult for anyone or anything to penetrate an aura that is healthy and strong.



          HOW TO KEEP YOUR AURA HEALTHY:

Clear your aura with white sage, copal or Tibetan incense on a daily basis. (It’s recommended to do this at the end of your day to clear any negativity or stress that has be collected through out the day.)

Spray yourself and/or your home with holy water. (Use a spray bottle so you can mist the water over you. Never drink holy water is can make you sick.)

Get 15 mins of sun a day. (Negative energies do not like sunlight)

If you feel your energy is “off” due to attacks you can have an energy worker clear your aura and align your Chakras.

Make positive personal affirmations for yourself.

Keep a loving and caring attitude towards others.

Include time for prayer and/or meditation on a daily basis.

Practice deep breathing exercises when you become fearful and anxious. Fear can be a helpful response to something that can be harmful to us or even life treating, so we know to protective ourselves, but in some case, when dealing with ghost or other entities it can be your enemy. They thrive on your fear, feed off of it, therefore the more you fear them, the stronger they become. Best thing to do but not always the easiest, is to try and remain calm, keep your “poker face” on, evaluate the situation and if you feel you must leave, just calmly walk away. Try not to give them what they need and want.

There are various gem stones that you can carry in your pocket or wear in jewelry to help with protection, grounding and put you in touch with higher vibrational beings, such as angels.