The phrase "hats off" is an idiomatic expression used to convey admiration or respect for someone's achievements, effort, or bravery. It originated from the traditional gesture of removing one's hat as a sign of respect, particularly in historical or formal contexts.
The expression "hats off" can be traced back to the longstanding custom of removing one's hat in the presence of someone of higher status or authority as a sign of respect. The act of doffing (lifting) one's hat dates back to medieval times when hats served as symbols of honor and social standing.