newline

A newline is the character or sequence that marks the end of a line of text and the start of a new one. In ASCII and Unicode, the common newline forms are line feed (LF, U+000A) and carriage return (CR, U+000D). Together, a CR followed by an LF can form a single end-of-line sequence in some contexts.

Platform conventions differ. Unix and Unix-like systems typically use LF as the newline character. Windows systems use a CRLF sequence. Early classic Mac OS used CR alone, but modern macOS and iOS use LF, aligning with POSIX conventions. In many network protocols, CRLF remains a standard end-of-line sequence.

In programming and data formats, newlines are often represented in strings with escape sequences: \n for LF, \r for CR, and \r\n for a CRLF sequence. Unicode also defines separate characters such as the line separator (U+2028) and the paragraph separator (U+2029), which are supported in some contexts but uncommon in ordinary text files.

Newlines influence editing, rendering, and data processing. Text editors display line breaks, and diff tools rely on line-ending conventions to show changes. Cross-platform development frequently requires newline normalization, sometimes involving text vs. binary modes and tooling that converts or preserves line endings.

Certain protocols specify newline forms. For example, HTTP uses CRLF to terminate header lines, and many email standards require CRLF as well.

A final newline—the convention of ending a file with a newline character—is common in programming and text processing. Some tools expect it and may issue warnings if a file ends without one, while others treat it as inconsequential.