A bracket is a type of punctuation mark used in writing to indicate the omission or interruption of a sentence. It typically consists of a pair of vertical lines, with one line slanted at the top and the other at the bottom, connected by an arched line that follows the curve of the brackets. Brackets are commonly used to enclose explanatory material, such as comments, clarifications, or additional information, within a sentence. They can also be used to indicate alternative phrasing or options in a list.