Definition & Meaning of "[smooth] {one's} ruffled feathers"

What is the origin of the idiom "smooth one's ruffled feathers" and when to use it?

The idiom "smooth one's ruffled feathers" originated from observing how birds behave when they are upset or threatened. When birds get agitated, their feathers become messy and stand up. People noticed this and started using the phrase to describe calming someone who is upset or offended. It means to make them feel better by addressing their concerns or apologizing. The phrase compares human emotions to the appearance of ruffled bird feathers. It's like gently smoothing down the feathers to make things peaceful again. It is often used in various situations where there is a need to address conflicts, ease tensions, or restore harmony in personal relationships, social interactions, or even professional settings.