The primary purpose of punctuation is to ensure the clarity and readability of writing. Punctuation clarifies sentence structure, separating some words and grouping others. It adds meaning to written words and guides the understanding of readers as they move through sentences. Often people advise that commas are used as a "pause" or a "breath" in a sentence, but that's not really all that helpful in providing technical rules or guidelines. And there are, in fact, some fairly technical rules and guidelines when it comes to using the comma usage.