The GCC or GNU Compiler Collection is a set of compilers developed by the Free Software Foundation (FSF) that are used to compile code for different programming languages. The GCC compiler is free and open source, which means that anyone can use, modify, and redistribute it without any license fee.

However, to ensure that the GCC compiler remains free and open source, the FSF has created a license agreement called the GNU General Public License (GPL). The GPL is a legal agreement that governs the use of software that is distributed under the GNU project, including the GCC compiler.

The GCC license agreement, also known as the GCC Runtime Library Exception, is an additional clause that provides an exception to the GPL. The exception allows developers to use the GCC compiler with proprietary software without violating the terms of the GPL.

This exception applies to the runtime libraries that are used by the GCC compiler when linking with other software. The exception allows developers to link their proprietary software with the GCC runtime libraries without requiring that the entire software be licensed under the GPL.

The GCC license agreement ensures that the GCC compiler remains widely available to developers, regardless of their preferred software licensing model. It also ensures that any software that is compiled using the GCC compiler remains open source and free to use, modify, and distribute under the terms of the GPL.

In summary, the GCC license agreement is an important aspect of the open source software movement, as it allows developers to create and distribute software that is both proprietary and open source. By providing this exception to the GPL, the FSF ensures that the GCC compiler remains a valuable tool for developers for years to come.