What's C?

C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system.

Although C was designed for implementing system software,  it is also widely used for developing portable application software.

C is one of the most widely used programming languages of all time and there are very few computer architectures for which a C compiler does not exist. 

C has greatly influenced many other popular programming languages, most notably C++, which began as an extension to C. [wikipedia]

Of course, we can see that to be a good C programmer you must be heavely bearded.