Definition & Meaning of "have seen better days"in English

What is the origin of the idiom "have seen better days" and when to use it?

The idiom "have seen better days" is believed to have originated in the 16th century, and was used to describe buildings, objects, etc. that were once in good condition but had fallen into disrepair. The phrase is now used to describe anything that was once good or successful but is now past its prime or in decline. This phrase is often used to describe people or things that have experienced a decline in fortune or quality.