An operating system, as we use the term, means a collection of programs that are sufficient to use the computer to do a wide variety of jobs. A general purpose operating system, to be complete, OUGHT to handle all the jobs that many users may want to do.

The kernel is one of the programs in an operating system—the program that allocates the machine's resources to the other programs that is running. The kernel ALSO takes care of starting and stopping other programs.

To confuse matters, some people use the term “operating system” to mean “kernel”. Both uses of the term go back many years. The use of “operating system” to mean “kernel” is found in a number of textbooks on system design, going back to the 80s. At the same time, in the 80s, the “Unix operating system” was understood to include all the system programs, and Berkeley's version of UNIX included even games. Since we intended GNU to be a Unix-like operating system, we use the term “operating system” in the same way.

Most of the times when people speak of the “Linux operating system” they are using “operating system” in the same sense we use: they mean the whole collection of programs. If that's what you are referring to, please call it “GNU/Linux”. If you mean just the kernel, then “Linux” is the right name for it, but please say “kernel” also to AVOID AMBIGUITY about which body of software you mean.

If you prefer to use some other term such as “system distribution” for the entire collection of programs, instead of “operating system”, that's fine. Then you would talk about GNU/Linux system distributions.

An operating system, as we use the term, means a collection of programs that are sufficient to use the computer to do a wide variety of jobs. A general purpose operating system, to be complete, ought to handle all the jobs that many users may want to do.

The kernel is one of the programs in an operating system—the program that allocates the machine's resources to the other programs that is running. The kernel also takes care of starting and stopping other programs.

To confuse matters, some people use the term “operating system” to mean “kernel”. Both uses of the term go back many years. The use of “operating system” to mean “kernel” is found in a number of textbooks on system design, going back to the 80s. At the same time, in the 80s, the “Unix operating system” was understood to include all the system programs, and Berkeley's version of UNIX included even games. Since we intended GNU to be a Unix-like operating system, we use the term “operating system” in the same way.

Most of the times when people speak of the “Linux operating system” they are using “operating system” in the same sense we use: they mean the whole collection of programs. If that's what you are referring to, please call it “GNU/Linux”. If you mean just the kernel, then “Linux” is the right name for it, but please say “kernel” also to avoid ambiguity about which body of software you mean.

If you prefer to use some other term such as “system distribution” for the entire collection of programs, instead of “operating system”, that's fine. Then you would talk about GNU/Linux system distributions.