Definition & Meaning of "be (like) child's play"in English

What is the origin of the idiom "be child's play" and when to use it?

The idiom "be child's play" is said to describe a task or activity that is very easy and simple to accomplish, as if it were something a child could do without difficulty. The origin of this phrase is straightforward; it likens an easy task to the kind of play that children engage in effortlessly. The idiom has been used in the English language for a long time, with documented usage dating back to the 17th century.