Whats with Twitter? I don't get it.?

[Sarv]

Usually, I think, personal celebrity accounts are personal. It is possible that
@theellenshow is managed by her managers.

Hashtags is a way to put a tweet in a specific topic, some use them as ads.
You may find what a specific #hashtags mean at:
http://twubs.com/ or
http://whatthetrend.com/ or just google

Mentions i.e. @username can be viewed under mentions timeline of receiver's account
whether receiver follows you or not. The mentions timeline can be viewed by clicking
on @username in the sidebar of twitter profile. This is also publicly viewable if any
user performs a twitter search for @username.
But if receiver is not following you he will not view your tweet in his main timeline.

hope that helps