Purpose
perl, python and even php offer much more for the programmer and system administrator than does awk. However, awk is available on practically all platforms, and can do virtually everything as well as perl or python. Awk scripts tend to be faster than perl scripts, and it requires far less disk space (figure about 1.5 megabytes for a full Gnu Awk installation, or 20 MB for a relatively full perl installation).
In these slides you will find a link to a beginning awk tutorial. There is more to be done with awk, however. It can handle network processes and is far more capable than most people realize.