Most paranormal investigators know that there are two main types of hauntings: residual, and intelligent. There is a third type of haunting, generally referred to as a daemonic haunting.  It is my humble opinion that a haunting of this type will absolutely fall under the intelligent haunting category.  So we will speak of the two main types here.

A residual haunting shows you a scene or some type of image that does NOT appear to recognize you, see you, or interact with you.  Examples of this would be a ghost walking into a wall and disappearing without  noticing you, seeing a ghost performing what looks like regular things, as if they are not aware of their death. They would appear to be living a normal life, oblivious to you.  At times, these spirits could even walk seemingly right through you and not notice.  If this happens, you could experience coldness or heat, lightheaded feelings, a moment of forgetting, tingling all over the body, dread, thrill, or any combination of these sensations.  It is this type of haunting that is tough at times on an investigator.  We always want to see if we can help a wandering spirit, and when we can't seem to get through to them, it leaves us feeling a bit helpless.  We recently did an investigation at a Famous Bed and Breakfast, and heard conversation by several ghosts in a  room where they seemed not to have any recognition of us at all.  Could this have been a residual conversation?  Very likely.  However, later in the evening, a voice from that conversation did speak the name of one of the investigators.  So it is possible to have both types of hauntings at the same time.

Ghosts can manipulate energy in every conceivable way.  They can manifest themselves as orbs, mists, fogs, in thick swirling ectoplasm, or as shadow figures in any shape or size. (Orbs are the most common form of spirit energy, as it takes less energy for this than to form a larger mass of form.)  They can move objects, throw things, grab you, push you, and even cause harm if provoked.  Ghosts can show you lights in the darkness, where no possible light source was.  They can fly by you with incredible speed, and leave you with nothing but the breeze of their passing.

I have been in an abandoned infirmary kitchen where there had been no one for years, and smelled bacon and eggs, as if they were being cooked while I was standing there.

Remember also, that the ghost population includes any type of animal, as some have said they still have their family pet with them, even after the physical death.

Ghosts can absolutely be attached to objects that were in their possession at the time of their death, and can go with those objects to different locations if they want to.  We call this object attachment. For this reason, you will see that there are many antique stores that have paranormal activity.  We have investigated shops where we got extraordinary findings.  Having said that, realize that an item you purchase from one of these shops has the possibility, although extremely rare, of spirit possession.   

Ghosts can and WILL grow tired of you at times.  I have had thirty and forty minute conversations with spirits and then all of a sudden they just leave, without regard to you.  Remember they will never feel obligated to have to answer to you.  When speaking or dealing with a ghost, they will always want the upper hand, and you will have to be very resolute to have any sort of control of the situation.  At times, they will say goodbye, or even ask you to stay, but this is rare.  And if you have this type of encounter, you should feel good about being a person that a lost spirit wants to try to communicate with.  In our experiences, the longer you get the spirit to speak, the easier it has been for us to have control of the situation.  When you stop to listen to your children speak, do they not feel better that you acknowledge them?  A ghost may get recognized once a month, or a year if they are in an abandoned building.  Their need to communicate may be the one need they have above all else.  Remember in this field of ours, we are reaching out to lost souls.  No one, including myself, knows why they are still here, but I know they shouldn't be.  And some of these spirits don't even know where they are, or that they are dead.

To certain types of investigators, ghosts can project their feelings and emotions on them.  I have an empathic ability, which means I can feel the pain that some ghosts felt at the moment of their death, or the last moments of their life.  The most incredible pain I have felt from a ghost was when I went near a hanging tree from the old days, and as I approached it, felt like I was literally being hanged.  The choking sensation was so intense I nearly blacked out, and had what appeared to be rope marks on my neck. I did not feel this was a daemonic oppression, but simply the last moments of a person that had been hanged on the tree.  There was no dark or sinking feeling, no oppressive smell, no feelings of dread, just intense pain from someone's last moments of life.  And when I could breathe again, I went back to the tree, and got no further sensation, nor any further readings.

The third type of haunting is a daemonic haunting, and is extremely rare to encounter.  In our experience, over 35 years of investigating have only led us to a handful of these hauntings.  A daemonic haunting is a spirit form that has NEVER been human.  They are from a different plane of existence, and will always have an agenda.  They will not just hang out in an earthly place, they are there for some purpose.  Remember that biblically,  angels and daemons battle around us at all times.  See Carl Johnson's writings on this type of haunting HERE.  Carl is one of the foremost demonologists in our field, and he works with the TAPS organization.   

I don't know anyone that can tell me why ghosts are here.  No one can explain to me why we hear children screaming and crying at a memorial where a school fire killed more than 80 people in the early 1900's.  No one can explain to me how we hear a woman singing at the place of a murdered teenage boy.