The elegant style of the examples makes this a joy to read.

See also:

• The elements of programming style
  

Another classic on writing supportable, lucid programs.

•  The C Answer book
  

A companion book with answers to the exercises)

C is still an influential language in use today, and this is the most concise statement instructing people in its use.  Examples are brief and clear.  Documentation of the functions is complete (can you say brief in the same breath as API for your language?).  By this, the 2nd edition, the language had been standardized.  In the MIT jargon file, a primer on computer culture from the old days, this volume is referred to as "the Old Testament".

C syntax has become extremely popular with a large number of programming languages which have imitated it.  This includes the fabulously popular C++ (which isn't really a whole new language) and Java.