I like to listen to classical music with violins. I wonder when violins were invented?
i have no idea when it was invented ,however they hollow wooden bodys
Yeah, do you know how many strings a violin has? I think three of four.
i believe so, they are very prominent instrument in western classical music
For sure. Every orchestra I have seen has violinists. They sound really good with the performance.
the left hand is used to regulate the sounds length of the strings , 
Oh ok. And the right hand holds the bow right? Can a violin be plucked like a guitar as well?
i dont thinks so but the classical guitar is one of the very few polyphonics instruments