Zettel is a collection of notes by Ludwig Wittgenstein (1889–1951), written between 1929 and 1948 and personally selected by him as the most significant for his philosophy. The collection may have been intended for future publication or use in other works.

The notes address all the main topics that occupied Wittgenstein throughout these years and up until his death. The formulations of key questions and possible answers—such as what is language, a proposition, the meaning of a word, language games, everyday life, machines, pain, color, learning the use of words, and much more—are presented in this collection as clearly as is possible for Wittgenstein. They are multifaceted and not without literary elegance.

Zettel is an essential source for understanding his philosophy and the potential it holds for philosophical work today.