Fact

[Julian]

The place most people in the world tend to think their opinions reside...

[Jason Yan]

That which is founded in truth.

[Sarah]

Making a statement, whether true or not, and finishing off with the word fact in capital letters, so to add emphasis and complete authority.

[Kai]

When somebody adds Fact to the end of their sentence, they are usually stating a controversial opinion, as if the addition of the word makes it so just because they said so.
Usually it is a sign of unwarranted self-importance.

[Cami]

see [taint] as its the best answer to what a fact is

[Dave Paprocki]

a piece of information about circumstances that exist or events that have occurred; first you must collect all the facts of the case
a statement or assertion of verified information about something that is the case or has happened; he supported his argument with an impressive array of facts
an event known to have happened or something known to have existed; your fears have no basis in fact; how much of the story is fact and how much fiction is hard to tell
a concept whose truth can be proved; scientific hypotheses are not facts