Question

The concepts and usages of "Who, What, Where, When, Why, &How

The comma is a punctuation mark, and it appears in several variants in various languages. It has the same shape as an apostrophe or single closing quotation mark in many typefaces, but it differs from them in being placed on the baseline of the text.

Punctuation can be confusing. Even self-proclaimed Grammar-phobes would profess to knowing how, and when, to end-punctuate with a question mark, period, and exclamation point. However, I venture to say that most novice and seasoned writers could use a sentence-ender refresher.