Question

What is a semi colon used for?

Answer 1

To stick two sentences together, basically. "He's recently married. His wife is over there." Becomes, "He's recently married; his wife is over there." It really doesn't get used very often, and doesn't need to be.

Answer 2

I like to use semicolons; I think that they're very useful.

See how they're written like a mash between a comma and a period?

That's their use-
not quite a comma that joins two incomplete sentences,
not like a period that separates two complete sentences,
but a tool that joins together two complete sentences.

Answer 3

more importantly those two sentences should have a relation not just any two sentences.

Answer 4

They're used to connect two independent sentences of a related topic!