Ctags generates an index file of C language objects found in C source and header files. The index makes it easy for text editors or other utilities to locate the indexed items. Ctags can also generate a cross reference file which lists information about the various objects found in a set of C language files in human readable form. Exuberant Ctags improves on ctags because it can find all types of C language tags, including macro definitions, enumerated values , function and method definitions, enum/struct/union tags, external function prototypes, typedef names and variable declarations. Exuberant Ctags is far less likely to be fooled by code containing #if preprocessor conditional constructs than ctags. Exuberant ctags supports output of Emacs style TAGS files and can be used to print out a list of selected objects found in source files. Install ctags if you are going to use your system for C programming.