; can be used to separate parts of a sentence which need clearer separation than would be shown by a comma, to separate main clauses which have no conjunction between, and to separate phrases and clauses containing commas
, is used to keep distinct information separated. It helps the reader understand how the ideas in the sentence work together. Although many writers benefit from reading aloud commas as pauses while proofreading, a comma does not always represent a pause in a spoken sentence.
