C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories. It is one of the most widely used programming languages of all time. See Wikipedia article.
Cscope is the de-facto tool for browsing C code. The package is bundled with xscope.el library which enables use of cscope from within Emacs.
gdb can be used for debugging.