To Do is often used in a Personal Information Manager for things which have not been completed. This is a more universal version than that of comments made in source code. It is often scratched down on the back of envelopes, napkins from lunch, a 3 by 5 card, or in a formal notebook dedicated to Time and Information management.
Enjoys a small amount of use to tag To Do items on some wiki pages; click on the title of the page and maybe you can help the author out.
TODO is often found in code indicating that something isn't completed yet. This has become so common that there's now an official @todo Java Doc tag. Most pages on the wiki citing To Do are using the term in this way.
/**
@todo :
take over world
/
Pros and cons discussed on the more general Fixme Comment page (critique by M.A. moved there).
See original on c2.com 