endlines

Endlines, or line endings, are characters or sequences that signal the end of a line of text. They originated from teletype machines and ASCII control characters, and in most modern systems are encoded as one or more characters. In Unicode, there are also dedicated line separator characters, but these are rarely used as simple end-of-line markers.

Common forms include LF (U+000A), CR (U+000D), and CRLF (U+000D followed by U+000A). Unix-like systems primarily use LF, Windows uses CRLF, while classic Mac OS used CR. Some contexts in older systems or specific protocols may use other markers; however CRLF and LF are by far the most widespread today.

Impact: Applications reading and writing text must decide how to represent and translate endlines. In programming languages, newline is usually expressed as escape sequences, such as \n, \r, or \r\n. Many languages and libraries support universal newline handling, treating any of the common sequences as a line terminator when reading, while preserving a canonical representation in memory or on output.

Cross-platform issues: Different endlines cause diffs and patch issues in version control and can cause scripts to break; tools like git offer options such as core.autocrlf to normalize line endings on checkout and commit. Text editors and IDEs may auto-convert endlines; some require configuring the preferred EOL style.

Summary: Endlines are a practical convention to mark line boundaries in text, with LF, CR, and CRLF forming the main variants; understanding them is important for cross-platform text processing, data exchange, and software development.