Definition & Meaning of "hook, line, and sinker"

What is the origin of the idiom "hook, line, and sinker" and when to use it?

The idiom "hook, line, and sinker" finds its origin in fishing terminology, representing the complete apparatus used to catch fish. The "hook" is the actual fishing hook, the "line" is the fishing line, and the "sinker" is a weight that ensures the bait sinks to the desired depth. The idiom has been adapted into everyday language to describe someone who has been completely and unquestioningly deceived or fooled.