It was called "C" because many features derived from an earlier compiler named "B". In fact, C was briefly named "NB". B was itself strongly influenced by BCPL. Before Bjarne Stroustrup settled the question by designing C++, there was a humorous debate over whether C's successor should be named "D" or "P" (following B and C in "BCPL").
Partly due to its distribution with Unix, C became immensely popular outside Bell Labs after about 1980 and is now the dominant language in systems and microcomputer applications programming. It has grown popular due to its simplicity, efficiency, and flexibility. C programs are often easily adapted to new environments.
C is often described, with a mixture of fondness and disdain, as "a language that combines all the elegance and power of assembly language with all the readability and maintainability of assembly language".