Paragraph
A paragraph (from the Ancient Greek παράγραφος paragraphos, "to write beside" or "written beside") is a self-contained unit of a discourse in writing dealing with a particular point or idea. A paragraph consists of one or more sentences. Though not required by the syntax of any language, paragraphs are usually an expected part of formal writing, used to organize longer prose.
History
The oldest classical Greek and Latin writing had little or no space between words, and could be written in boustrophedon (alternating directions). Over time, text direction (left to right) became standardized, and word dividers and terminal punctuation became common. The first way to divide sentences into groups was the original paragraphos, similar to an underscore at the beginning of the new group. The Greek paragraphos evolved into the pilcrow (¶), which in English manuscripts in the Middle Ages can be seen inserted inline between sentences. The hedera leaf (e.g. ☙) has also been used in the same way.