تعریف و معنای "[strike] while the iron [is] hot"

What is the origin of the idiom "strike while the iron is hot" and when to use it?

The idiom "strike while the iron is hot" has its origins in blacksmithing, where iron is most malleable and easy to shape when it's heated to the right temperature. In a figurative sense, it means taking advantage of an opportunity or situation when the conditions are favorable or at their most advantageous.