This talk will discuss approaches for debugging codes. We will start with freely available open source debuggers such as gdb and those supplied with the compilers, such as PGI's pgdbg. Then we will focus on features of the commercial DDT debugger which CHPC licenses. DDT can be used for debugging serial and parallel C/C++ and Fortran programs running both on CPUs and GPUs. We will then talk about other more specialized debugging tools such as the Intel Inspector. We will close with some hints on debugging interpreted languages such as Matlab, Python or R.