Antonio Vivaldi is a fun character in music history. He became a priest in Venice, but got out of saying mass regularly. He was able to use that status to basically coast off of while he spent most of his life writing concertos and opera. He directed an orchestra of orphan girls at the Pieta hospital, and would have them perform at church regularly. It was these girls that he wrote his concerti for, mostly. In a little historical background, apparently many of the girls were not actually orphans, but were basically the bastard children of the nobles who were abandoned. Vivaldi was also a major opera composer at the time, although his forays into that genre are not as well remembered today. Somehow, despite being decently popular in his lifetime, he ended up dying in Vienna too poor for anything but a pauper's grave.
Vivaldi was very influential in the form of the concerto, creating a style that Bach emulated soon after. His concertos, unlike those later on, were written mostly for strings, including the orchestra, although he would occasionally use bassoons or flutes and the like as soloists too. His concerti use the ritornello form that was so prominent in that time period, which basically meant that there were contrasting sections of a work where the orchestra would play a theme, and then the soloist would play a section, and then the orchestra would come in again, repeated until the end of the movement. Vivaldi's two most notable collections of concertos are his opus 3, L'estro Armonico, and his Opus 8, The Contest Between Harmony and Invention. Opus 8's first four entries are called The Four Seasons, because they are accompanied by sonnets that we think Vivaldi wrote detailing the program of the music. If you read the text, you'll actually find a lot of stuff that is very obviously corresponding to the sonnets. The concerto form at this time solidified into the standard setting of a fast movement, then a slow movement, then another fast movement. The selections today will be Spring, Fall, and Winter. My recording recommendation is of Gil Shaham and the Orpheus Orchestra, which is in my opinion the best made recording of the work, because it keeps it's baroque feel intact but is kept from every being stuffy. Also on there is a recording of Fritz Kreisler's Concerto in C, that is supposed to emulate Vivaldi. Kreisler is the most important violin player from the early 20th century, and for some unknown reason, he would frequently write music then try to perform it as if it were written by some other, long dead composer. He is still played, mostly because of his arrangements for violin and piano of things like the Devil's Trill sonata.
Here are the videos. To wit, I'm not as enamored of the performance in them as I am of the Gil Shaham recording, but they will work for now, and if you're into sand painting, I guess they'll be up your alley.