In punctuation, a period or period (Commonwealth and wider Commonwealth English) or a period (North American English) is a punctuation. It is used for many purposes, the most common of which is to mark the end of a sentence (except for questions or exclamation points); the final use of this sentence is a period. Characters are usually placed after the initial used to represent a name; sometimes appear after each letter in the form of an acronym (for example, "U.S.A."), although this style is declining; and often used at the end of other abbreviations - in the UK, mainly truncation like Rev., rather than contraction like Revd; but they are all American English. There are also many situations in mathematics and calculation of whole point, which can be called point (abbreviation of decimal point) or point here. Full point glyphs are sometimes referred to as baseline points, because in printing, they are points on the baseline. The term distinguishes it from the middle point (convex start point). Although period technically applies only to the end of a sentence, the distinction (at least since 1897) does not exist in all modern style guides and dictionaries.