How such documents are actually stored depends on the file format. For example, HTML uses the <p> tag as a paragraph container. In plaintext files, there are two common formats. The pre-formatted text will have a newline at the end of every physical line, and two newlines at the end of a paragraph, creating a blank line. An alternative is to only put newlines at the end of each paragraph, and leave word wrapping up to the application that displays or processes the text.

A line break that is inserted manually, and preserved when re-flowing, may still be distinct from a paragraph break, although this is typically not done in prose. HTML's <br /> tag produces a line break without ending the paragraph; the W3C recommends using it only to separate lines of verse (where each "paragraph" is a stanza), or in a street address.[5]

Numbering
Main article: Dot-decimal notation
See also: ISO 2145
Paragraphs are commonly numbered using the decimal system, where (in books) the integral part of the decimal represents the number of the chapter and the fractional parts are arranged in each chapter in order of magnitude. Thus in Whittaker and Watson's 1921 A Course of Modern Analysis, chapter 9 is devoted to Fourier Series; within that chapter §9.6 introduces Riemann's theory, the following section §9.61 treats an associated function, following §9.62 some properties of that function, following §9.621 a related lemma, while §9.63 introduces Riemann's main theorem, and so on. Whittaker and Watson attribute this system of numbering to Giuseppe Peano on their "Contents" page, although this attribution does not seem to be widely credited elsewhere.[6] Gradshteyn and Ryzhik is another book using this scheme since its third edition in 1951.