In JavaScript, expressions are phrases that the interpreter can evaluate. For example,

x + 10

x < 10

x = 10

In linguistical terms, JavaScript is made up of sentences, phrases, and words. The sentences are JavaScript statements, in which an entire action is expressed. The phrases are JavaScript expressions, in which the elements of the action can be created and put together to make a statement. The words are JavaScript operators, which are used to act upon the data passed to them.