Intelligence is the ability of living creatures

to process information

... is ability ...

It is one of those biological traits , that determine effectiveness of a subject in situations, in which the goal of his efforts is clear.

... to process information ...

Information is every change, which a subject discriminates. In the definition a crucial word is to process. Intelligence does not express in processes in which information is only transmitted. It is important that a subject processes information in a way that is new for him.

... living creatures ...

Intelligence is not only man's ability. It is an ability of all living creatures who process information with a central nervous system.