Question

What are the most common/frequent memory leaks programmers use to run into when developing applications?

Interested in all kind of languages, would be nice if this could evolve into a community wiki where to see fixes for common leaks in different languages.

Update

I have a suggestion to limit this conversation to C related languages, .NET and Python. I think these are often used languages, and often beginners try to work with these. In case more languages are needed, edit.

Answer 1

EDIT this to add similar points.

In C++,

1. Forgetting to delete a pointer object.

In PHP,

1. PHP takes cares of memory management. It automatically deletes the memory of a variable when it goes out of scope.
2. On long running PHP scripts, it’s a good idea to manually close unneeded socket connections, free result objects, etc.

In .NET

1. Failing to unregister event handlers.