On the Internet, we met such an expression TODO, TODO-LIST, TODO-application, but nowhere is not said what it is. This is the same, if not, what does it differ?

Answer 1, Authority 100%

This is a simple list of tasks. It is needed to control and not forget the cases you need to do the day. And TODO can be interpreted in different ways, but it means the same thing, this is a list of cases / tasks.

Here is an example of the TODOIST application. Very comfortable and easy to use.