Most important things about C++ templates… lesson learned

Question

What are most important things you know about templates: hidden features, common mistakes, best and most useful practices, tips...common mistakes/oversight/assumptions

Answer 1

This may not be popular, but I think it needs to be said.

Templates are complicated.

They are awesomely powerful, but use them wisely. Don't go too crazy, don't have too many template arguments... Don't have too many specializations... Remember, other programmers have to read this too.

And most of all, stay away from template metaprogramming...