C may refer to
- C (letter): The third letter of the English and Latin alphabets.
- Programming languages: A formal language specification, and programs for translating the formal language to machine code.
- C_programming_language: General-purpose procedural programming language developed in 1972. - created in the 1970's at Bell Laboratories
- C++: Programming language created by Bjarne Stroustrup that added concepts from object oriented programming to the C programming language. - created in the 1980's at Bell Laboratories
- C#: Object-oriented general-purpose programming language developed for the Microsoft .NET Framework. - first released in 2002 by Microsoft
- C, musical note
- 'C', the codename for the head of SIS (MI6), the British secret intelligence service (currently Sir John Scarlett)
- The unit coulomb
- c, the speed of light