A form of disapproval like smh

Stops a sentence. It's end punctuation.

It's that simple. Or is it? Usually it's used (in text) nowadays to symbolize someone being angry or upset.
Or it's used in its form "." (in text)), which to be honest is kinda stupid. If you're not gonna say anything, don't say anything at all~.

Its a dot or a point

Code a girl uses to tell usually a male friend they are on their period

.

.

A marking that allows Tumblr users to make an essentially "blank" post when they are upset and just want to write in the tags.