Meantone tuning began in the 15th Century and lasted until the 19th Century. The tuning method tunes the intervals of a perfect third and perfect fifth equally.
Well temperament was a method of tuning so that all 24 musical scales would sound equally well when played, used in Mozart's time.
Thomas Young used a tuning method where all the keys were balanced around D and G-sharp. This method allowed for C to G to sound sweet, and the black notes to sound somber and stern.
Just intonation uses an acoustically pure method of creating intervals by equating notes to fractions, basing all of the other tones on a note designated as 1/1. It is a modern alternative to equal temperament.
Equal Temperament is the modern approach to tuning, using a machine to calibrate the notes to where they are equal divisions of twelve.