If you use only a wimpy comma to connect the two sentences, the combination becomes what’s called a “comma splice,” also known as a “run-on sentence” or a “fused sentence.” “She is tall and thin; she ...

This sentence has two clauses. Think of a clause as a subject and a verb. And in this sentence both clauses are fully independent, meaning they could stand on their own as sentences.

Those commas look weird, they break up the flow of the sentence and now I know they're unnecessary in a case like this. The Chicago Manual of Style explains why not all quotations take commas.

Those commas look weird, they break up the flow of the sentence, and now I know they’re unnecessary in a case like this. The Chicago Manual of Style explains why, though many quotations take ...

Truss, a former BBC programme presenter, would be annoyed with the writer of the three sentences for needlessly using commas to split up the subjects from their verbs (predicates).

In the sentence example above about grandpa, the important piece of punctuation was a comma. Commas and periods are the most frequently used punctuation marks.