Hi Jim, I'm glad the answers that Matthew gave will prove helpful in your research. Now in response to your question about shadow entities this is the best way that Matthew knows to explain them. They are Earthbound Spirits, so they do know they are gone and are aware of you. They seem to possess a childlike curiosity, sort of a "I can see you, but you can't see me" type of mentality. The ones that move fast, out of the corner of your eye, like to watch you, but don't want to be seen themselves, hence why they make a quick exit. They appear darker, or as shadows as they possess what could be called the closest thing to a corporeal body that a spirit form can take. They seem to become attached to a person or to a certain place. You can tell them apart, not only from their appearance, which tends to be dark, almost black in color, but by the type of feeling or atmosphere around them. Usually tending to be benevolent and curious, they may make you feel anxious or nervous for no reason. While as ghosts tend to create an oppressive feeling around them. If you engage them in conversation, you will notice that they will respond to you, in whatever way they are able to. And react depending on your request. What you will notice is a displacement of energies as the entity tries to comply. These are the only entities you can actually sense their movements about you.

Generally these are not what you would consider an 'evil' spirit, the darkness of spirit comes from the soul itself. Those that were 'evil' in life, will tend to be the darker and more 'evil' spirit. Basically, what you are in life, you will be in death. Or the afterlife.

I hope that this explains the mystery surrounding these entities. If you have anymore questions for Matthew, please feel free to e-mail.

In answering your questions, Matthew has posed a question for you, if that is alright. The question is this. What has caused you to actively research the other side?
 
Here is Jim's answer to Matthew's question:
http://ghoststudy.com/new6/jims_answer.htm