Definition - What does Objective-C (ObjC) mean?
Objective-C (ObjC) is a programming language that is used in the OS X and iOS operating systems and their application programming interfaces (APIs). Objective-C is object oriented, general purpose and adds to new language features in the C programming language. Originally developed in the 1980s, Objective-C was used by some of the earliest operating systems.
Techopedia explains Objective-C (ObjC)
Originally created by Brad Cox and Tom Love at their company Stepstone, the Objective-C programming language gained popularity with its use in NeXT computers. The language was soon linked with Smalltalk in order to expand the usability of both the languages. Objective-C programs that are generic and do not use external complex libraries can be complied in any system compatible with GCC or Clang. Extensions used for Objective-C source code are .m while header files are similar to C programming header files, meaning the .h extension. Objective C++ files have a file extension of .mm for their source code files.