What are data breakpoints?

I just came to know that there are data breakpoints. I have worked for the last 5 years in C++ using Visual Studio, and I have never used data breakpoints.

Can someone throw some light on what data breakpoints are, when to use them and how to use them with VS?

As per my understanding we can set a data breakpoint when we want to check for changes to a variable's value. In this case, we can set a data breakpoint with a condition on the variable value.