Most of the strings (violins, violas, etc) probably date to around the 17th century. They existed before then in various forms (the violin itself dates to about the 15th or 16th century in pretty close to its existing form), but the modern string orchestra really took form during the 17th and 18th centuries. Strings were more popular in the 17th century, with horns and flutes being added in the 18th century.
The “piano-forte” (now just called a piano) dates to about 1700. I have to wonder how many people realize it’s named for the Italian words for “quiet” and “loud” because, unlike the earlier harpsichord, it could play both quiet and loud music. Now it’s just called a “quiet” which is kinda funny if you ask me.
Absolutely, the basic layout and structure of the violin has stayed pretty much unchanged for centuries, but there’s differences between the setup of instruments now compared to 100 or 50 years ago (synthetic metal-wound strings, shoulder rests, etc.) which affect both the sound produced and also playing techniques.
Basic shape, construction, size, mechanics, acoustics, and sound produced. I’ll allow for changes in specific materials and accessories like shoulder rests. (In other words, consider synthetic metal wound strings to be the same as sheep-gut strings.)
