Used in an expression in some languages, this operator yields a boolean result, i.e., true or false. In others, it returns an integer value that you can pretend is a boolean. I have seen return values of 0 and 1 but also 0 and -1. It depends. A mathematical example:
10 <= 5 would evaluate to false whereas
5 <= 10 would evaluate to true
Also known as ≤ in some circles.
You can represent these symbols in HTML by means of the following HTML symbol references: <= or ≤ or ≤.
Thanks to mblase and Inoshiro_K and others for keeping me straight on the finer points.