Static:

The normal flow of elements. This is the default position of everything.

------

Absolutely positioned:

Removed from the flow of the document; their position in the html doesn't matter generally

An absolutely positioned item will try to be only as wide as is needed. 
- if you position something absolutely which only has text, and don't give it a width, it will only be as wide as the longest word

By default, show up on top of non-positioned items

Position themself against the first parent they encounter, working their way out, which has a non-static position. So we use relative positioning on the parent we want to position something against, with no offset (no left, right, top, or bottom values).

Will not cause their parent item to grow. Their parent item doesn't contain them in the normal sense anymore.

----

Relative:

Moves something relative to where it would normally sit.

If something is positioned relatively, the space that item would otherwise occupied is still reserved for that item, even though that item is moved out of it.

----

Fixed:

Just like absolute, but doesn't move with browser