u001B

U+001B, commonly known as the escape character or ESC, is a control character in Unicode and ASCII. It has the hexadecimal value 1B and the decimal value 27. The character is non-printable and is used to introduce control sequences rather than to display a symbol.

In practice, U+001B is most prominently used to start escape sequences in text terminals and related devices. Many terminal emulators interpret ESC as the initial byte of a broader sequence, such as the ANSI escape codes used for cursor movement, color changes, and text formatting. A common example is the CSI (control sequence introducer) sequence that begins with ESC followed by the left bracket, for instance ESC [ 31 m to set the foreground color to red, or ESC [ J to clear parts of the screen.

Across programming languages, the escape character is typically represented in source code as \u001b, \x1B, or ESC. In data streams and file formats, it appears wherever a device or protocol relies on escape sequences to convey commands or formatting rather than literal text.

The use of U+001B can have implications for security and data integrity, as terminal escapes can be misused in injection attacks or cause unintended behavior if not handled properly. Some environments sanitize or strip ESC sequences to mitigate such risks.