What does it mean to have a hard tail on a guitar?

A hard tail on a guitar refers to a type of bridge design that is fixed to the body of the guitar, meaning it does not allow for any pitch modulation through a tremolo system. This setup typically provides greater tuning stability and sustain, as there's less movement and potential for strings to go out of tune. Hard tail bridges are commonly found on many electric Guitars, especially in models designed for rock and metal genres.