GCC began as the GNU C Compiler, written by Richard Stallman as part of the GNU Project’s effort to build a complete free operating system. The GNU release history records that the first beta (version 0.9) appeared on March 22, 1987, with version 1.0 following on May 23, 1987. Development moved quickly that summer, with several point releases shipping within weeks of each other.
A free, portable, high-quality compiler mattered enormously. To build a free operating system you first need a free compiler, because almost everything else is written in C and must be compiled. GCC filled that gap, and it became the standard toolchain for the free software ecosystem and, later, for the Linux kernel and the GNU/Linux systems built around it.
Over time the project grew beyond C. As the official GNU pages describe, GCC was renamed the GNU Compiler Collection to reflect that it compiles many languages, including C, C++, Objective-C, Fortran, and others, and targets a wide range of processor architectures. This breadth is part of why GCC became one of the most widely ported pieces of software in computing history.
GCC is distributed by the Free Software Foundation under the GNU General Public License, which guarantees the freedom to run, study, share, and modify the compiler. That licensing choice tied the tool directly to the copyleft principle at the heart of the GNU Project.