Spirit entities can often attach themselves to an individual as well as a place.  The reason it may have moved from place to place with you is that you have not addressed its presence.  Also as the one that knows they are there, it is your energy that helps them manifest in spirit form.  They know you see them and are waiting for some kind of acknowlegement or communication.  

Strong grounding, protection and sense of self is important as you found.  Then just saying out loud who are you?  What do you want?  may elicit some information to aid in the moving on of the spirit entity.  At any rate it is the next step.

I did ask a couple of times who they were, I had thought that maybe it was one of my "friends" checking up on me. But as soon as I said it, it disappeared.  It felt like it didn't want me to acknowledge it, almost like it thought it was invisible to everyone.  
My question, why would a spirit entity attach itself to me?  I mean, would it be someone I know maybe or just some spirit that popped up or what?  What basis does it use to choose who to attach itself to someone??  (I only know 1 live person who may be that tall lol and it doesn't feel like him)

If it does not want to be acknowledged then perhaps it doesn't even realize how much your energy is what is used for the purpose of its manifestation.  You would be well to do some closing down so that your energies become your own.  Spirit can attach itself to us for many reasons - mostly the facts of compatibility.  In the sense that your energy is compatible with its own energy can it manifest.

It does not appear to have a bad purpose, but 'stuck' is still not the best place to be.  If it is a dark shadow to you, what is it to itself?

I've had a "shadow being" around my house for almost a year.  I finally got tired of it suprising me and I smudged my home.  No more shadow.

Shadow beings are not quite understood, yet.  The reports people have made, they are usually dark, flowing forms, lacking mass, much like a shadow, that moves very quickly, seemingly dancing, with no spatial constraints.  It seems to go where it wants regardless of walls, etc.  Many have reported them wearing a hat, often a fedora.  Many have glowing, red eyes.  Some feel 'menacing' or evil, some don't.  One of the most commonly reported characteristics is that it seems to appear, first, in our peripheral vision, only to "dart" through a wall or elsewhere, when we turn to face them.  

As to what these things are, it has been proposed that they are leftover flickers of life energy.  It has been suggested that there is a thin veil between our world and the ethereal and that occasionally they "overlap".  It is when this happens that we may catch a glimpse into this other realm in the form of the "shadow being".

Some cultures recognize them as being different from a ghost, in that there doesn't appear to be any "human" qualities to it.

I cannot say for certain that what you are experiencing is a shadow being.  I saw this thread and wanted to tell you about them, at least.

Namaste

Su

Suruha

Your brilliant!  How come you know so much about them and how can i find out more?

It wasn't until you said about wearing a hat that i remembered, yes the last one wore a hat and always a long trench coat or cloak.  That's why i thought of the grim reaper.  From the hight (over sized tall) and the no detailed face.  

I also remembered that when i saw it sometimes it seemed like the size of a medium sized dog, darting out of or passed the door.  I know this contradicts what i've just said about the over sizedness but what you said brought it back to me.  The darting off as soon as i looked at it.  Like watching me but running when it felt i was going to look at him/it.

When you say 'overlap' are they going about their business in their own plane or are they aware of us as well?

Do they have a proper name or just shadow people?