Ablank clause should always be separated from the rest of the sentence by commas

Independent clause uses commas to separate independent clauses when they are joined by any of these seven coordinating conjunctions: and, but, for, or, nor, so, yet.

Relative clause- makes additional comment or information about the referring noun is separated by a comma.

Carol, who wanted to go swimming, was stuck in traffic

rhyming octave and a rhyming sestet

if i'm wrong i'm sorry

d. cassius cannot believe that a weakling like caesar has become so great.