Operator

How you can describe operator purpose in computing?
Operator is generally like functions (with different syntax) with specific purpose and used very often. Usually operators defined by programming language itself.

In computer programming, operators are constructs defined within programming languages which behave generally like functions, but which differ syntactically or semantically.

Common simple examples include arithmetic (e.g. addition with +), comparison (e.g. “greater than” with >), and logical operations (e.g. AND, also written && in some languages). More involved examples include assignment (usually = or :=), field access in a record or object (usually .), and the scope resolution operator (often :: or .). Languages usually define a set of built-in operators, and in some cases allow users to add new meanings to existing operators or even define completely new operators.
— Wikipedia