Music existed before the Baroque period. There's the Renaissance, Medieval, the Romans and Greeks, the ancient civilizations, and the prehistoric times when people made flutes out of bones and played ancient music. But piano music as we know it had its beginnings in the Baroque period.
Baroque music saw the beginning of operas, the slow dominance of secular over sacred music, and the beginning of our major-minor system or tonality. It is characterized by several features: a dynamic rhythm based on the regular beat that drives the music, dance rhythms, continuous expansion, increasing expression, terraced dynamics (going from loud to soft without crescendos or decrescendos), and the dominance of the Binary Form.
One of the important instruments of this time is the harpsichord, which could be considered as an ancestor to our piano. The Baroque harpsichord had two keyboards for terraced dynamics. The strings were plucked by quills instead of struck with hammers as it is today, therefore it is not capable of many dynamic variations or sustained tones. This influenced the music of this time. Composers added ornaments to their music in order to counter the problem of sustaining notes. It was a good instrument for contrapuntal work, and Baroque keyboard music is largely contrapuntal. It was also a good instrument for figured bass playing which took place of the conductor. Meanwhile the early piano was invented in 1711 by Cristoforni. It was called pianoforte, or "soft and loud". But it did not become common until later.
The two most important composers of
this time were J.S. Bach and Handel. J.S. Bach (1685-1750)
was a great composer of the keyboard. was born in Eisenach,
Germany. He studied violin with his father and clavier and
organ from his brother. He worked at various places during
his life, often as an organist, kappelmeister, or cantor. At
his time he is known as the best organist in Germany and was
well known throughout Europe. His most important keyboard
work is The Well-Tempered Clavier, a collection of 48
preludes and fugues in all of the 24 keys to prove that the
new major-minor system is superior to the old systems. It has
been called the Old Testament of piano music. His piano work
is characterized by his mastery of counterpoint. His other
works for keyboard includes 6 Partitas, the Italian Concerto,
Goldberg Variations, A Musical Offering, 6 French Suites, 6
English Suites, and The Art of Fugue.
When playing a Baroque piece, you will often notice that they tend to involve more fingerwork than later works such as Chopin or Debussy. But not all Baroque keyboard pieces are contrapuntal -- for example, Adagissimo by Bach is in the style of a choral, as are some of his sarabandes. Counterpoint still prevails though, and often the key to playing Bach fugues/contrapuntal works is to practice tricky passages slowly until you master them, and then play firmly, keep in mind of rhythm integrity. Not too many tempo rubatos, but still breathe sometimes. More can be learned by experimenting and listening of Baroque works.