Question

When do you use a semicolon in a sentence?

I read it: bla bla bla bla;bla bla bla.
Me: What? Why do they use a semicolon?

Answer 1

The structure of a sentence may contain many variables; these can include dependent or independent clauses, verb or noun phrases, combinations of these, and syntax.

Explanation:

The sentence above is an example of the use of a semicolon. In the sentence it is used between two independent clauses that are both descriptions of the variables in a sentence.

Note that the second part of the sentence also consists of a number of topics separated by commas, so the semicolon distinguishes the first thought from the secondary grouping of descriptors.

Here is more information:
https://writing.wisc.edu/Handbook/Semicolons.html