# Operation

An operation, normally called a binary operation, is a calculation which combines two elements of a set to product another element of the same set.

For example:

In some contexts it's most natural to use the multiplicative notation, in other contexts it's most natural to use the additive notation, in yet other notations we can simply choose one or the other with neither choice being more natural, and sometimes we use an entirely different symbol.

When using the multiplicative notation sometimes the symbol is omitted altogether.

Other examples of binary operation are matrix multiplication and composition of functions.