A Little History
Objective-C is an object-oriented programming (OOP) language that was developed by Brad Cox in the 1980s, based on a programming language called Smalltalk-80. The language was layered on top of the C language, a key programming language that was developed at Bell Laboratories in the 1970s. Most of the UNIX operating system (also created at Bell Laboratories) was written in C, which is a language that provides extreme flexibility, allows access to system resources, and produces code that's fast and efficient.
Apple inherited Objective-C when it acquired NeXT Software in 1996. The release of Mac OS X, which was based on NeXTSTEP, saw the rise in popularity of the Objective-C programming language based on the corresponding rise in popularity of Mac OS X. In fact, most of the major applications in OS X (Safari, Mail, iTunes, Calendar, Contacts, and so on) are written in Objective-C.