How do people in the 1600s and early 1700s define what we today call baroque music?
There's a general term all over Europe, which is Latin: MUSICA MODERNA. So people back then called their music just MODERN MUSIC. Which doesn't help us much, since other generations have done that as well. But there was another term which is more speaking and still in use by modern experts: GENERAL BASS MUSIC or CONTINUO MUSIC (basso continuo = general bass).
There were several kinds of basso continuo (b.c.) music, plus more than one system to categorize them. Firstly, music was catergorized by nations, and there was mainly Italian, French, German and English music. In each of these nations b.c. music had a different character. Italian music was more soloistic, virtuosic and tended to spontaneous ornaments and free improvisation. French music was more danceable or tended to choirs and soloists often stood back. I know mainly the German music scene from original German sources. Music fans here are divided in followers of Corelli and followers of Lully. You may compare the Lullyists to disco fans and Corelliists to rock fans. It kind of was that way and I think it was all over Europe. Even high ranking members at the French court in Versailles were often music nerds and preferred Italian music. People who liked 'parties' and dancing likely preferred French music. Especially German composers tried to merge Italian and French styles into a specifically German style.
More divisions were church music (musica eclesiastica) and theater music. Church music could be a Motet, Cantata or Oratorio. Theater music could be an Opera, musical Comedy, or Pastoral (mostly popular love scenes in a shepherder environment, although there were also natitivity pastorals for Christmas). There were also secular Cantatas which were often performed at coffee houses or other places.
There's one more term, I know from Germany only. French music, which was meant for dancing was called "galante Music" (gallant music). Suites are compilations of gallant music. There are voices who argue, the movements in Suites were not meant for dancing. This is questionable. People back then loved parties (in Germany named with the French word "Assemblées") and balls. You had to be able to at least dance the Menuet to live a social life. Those who didn't dance were seen as asocial losers and often denied ambitious jobs. These people were constantly looking for music to dance to and there is no reason to not play a Menuet from a Suite on a party and dance to it. People discussed what to bring for eating and drinking, but they also asked the question, "Who is playing what instrument?" There were always hobby musicians around, for people could only have music when they played it. The next question was, "Who brings what notes?" It is all described with lots of details in books of dancing masters. As I recall from reading books of Handel's old Hamburger friend Johann Mattheson, Suites were often compilations of dances out of popular stage works. People certainly wanted to dance to titles which were popular, notes of Suites were to buy in shops and no composer would ask the buyer to not dance to them. In our days the baroque dance community still loves to dance to movements out of Suites and dancing to them works beautifully. Suites could be with large orchestral score or in rather chamber size.
Another division was Chamber Music, by small bands in small rooms. Chamber Music was neither church music nor stage music/ theater music. Little known is the term Chamber Dance, which is gallant dancing. It was not meant for stage, although elements of Chamber Dance could be integrated in ballet scenes of an Opera, Comedy, or Pastoral. If Chamber dance was figured it could be quite an art and presented with a chamber band and lyrical singers on various events, like balls or parties. The most common chamber music was the Sonata, featuring one, two or more solo instruments, whereas Concertos were kind of conversation between orchestral score and one solo instrument. The orchestra meant the place in a theater where the band was placed, which follows the original meaning of ancient Greek.
Apart from standard partner dance (mostly Menuets), there was a higher standard in galant music: Striving amateurs were eager to learn how to also dance Sarabande, Chaconne, Gigue etc. which was a mix from standard partner dance and techniques from ballet. There was even a higher standard to dance a Menuet, called Menuet figuré—also a way of figured dancing, adding steps and techniques from ballet.
My violin is a 3/4 violin, made for right-handed players, though I play it left-handed. As I felt she was the best in the shop of all 3/4 violins I tried and the luthier agreed. I prefer Obligato strings together with Eudoxa E string. Self-made bow, weight: 24 g / 0.85 oz