Lisp
In plain terms
A pioneering language family famous for treating code as data.
Going deeper
Lisp uses parenthesized list syntax and lets programs manipulate their own code via macros, making it endlessly extensible. It shaped functional programming and AI history.
Under the hood
Homoiconicity (code is data) enables uniquely powerful metaprogramming; dialects include Common Lisp, Scheme, and Clojure.
Examples
AI research, Emacs (Emacs Lisp), Scheme teaching, symbolic computation.
Think of it like...
Like clay that can reshape the very tools you're sculpting with.