Another violin post, yay! I'm sure many of you already understood what I was talking about in my previous post, but this topic will likely be new to those of you who do not play a string instrument.  Did you know that if you buy a new violin and just take it out and try to play it right away, it will make no sound? Now that's just crazy, right?  It may sound like it; but if this were to happen, it's because you missed one very important step.  You forgot to put rosin on your bow.  

A bow is made of horse hairs that are connected on each end to a stick that is typically made of wood or a synthetic material.  On their own, the hairs on a bow are very smooth; so if you were to rub them across the strings of a violin without putting on rosin, the bow would simply slide across the string without causing the strings to vibrate, which means no sound.  

When rosin is applied, it gives the bow some stickiness.  This will increase the friction between the hairs on the bow and the string.  Because of this friction, the bow will try to stick a little to the strings.  It will grab the strings, causing them to vibrate as you drag your bow across.  This is part of what makes a violin have such a clear sound.  You have to reapply rosin every now and then.  You start to notice that your violin isn't making much sound, especially when playing higher notes, when it is in need of more rosin.