The Band easily straps around the lower bout of the instrument, sitting between the bridge and the tailpiece. Because it picks up the mature sound vibrations from the belly of the instrument rather than the limited vibrations found in the bridge, the Band gives a clear, warm, full sound, unlike many other pickups which sound tinny and one dimensional. It needs no pre-amplification, phamtom power, or additional gadgets. You can simply strap it on, plug it into any amp, PA system, or even computer, and play or record. 

The advantages I've found in a pickup over a mic are that, as I said before, you're free to move about the stage, there is no bleed over sound from other people/instruments, no wind noise if you're outside, it fits into your case, there is no boom stand to lug around, and there is no chance of it dropping and breaking! 

The Band for violin runs about $120 and totally worth it! Good luck!