Định Nghĩa và Ý Nghĩa của "(at|) the end of the rainbow"

What is the origin of the idiom "the end of the rainbow" and when to use it?

The phrase "the end of the rainbow" is rooted in Irish folklore, where a leprechaun is said to hide a pot of gold at the point where a rainbow touches the ground. This idiom is used to describe something that is virtually impossible to find or attain, often conveying a sense of being in pursuit of an elusive goal.