S-expressions are used in the Lisp programming language and Lisp-derived languages such as Scheme and DSSSL, and as mark-up in communications protocols like IMAP and John McCarthy's CBCL.
S-expressions are used in the Lisp programming language which is a main feature of lisp and all of its dialects. Other uses of S-expressions are in Lisp-derived languages such as DSSSL, and as mark-up in communications protocols like IMAP and John McCarthy's CBCL.