A variable in C/C++ which stores the type and location of data in memory.
There's an old programmer's saying:
"The problem with C is that it is too easy to shoot yourself in the foot.
With C++ it is much harder - but when you do, you lose your whole leg!"
Most of the problems have to do with C/C++ pointers, and people not fully understanding how to use them.
- Here's a basic description on pointers, going to the very beginning.