An aircraft can go around for a number of reasons:
To answer cxsjr's question, the aircraft was probably in an undesirable attitude for landing. i.e. too fast, too high, failed to capture ils glidepath etc. In this instance all airlines have (slightly differing) regulations on when on an approach you should be fully established and configured for landing. If they are not, they go around and try again. Sometimes it is the flight crew who are not happy, maybe they have had t rush their descent and are not entirely happy so they try again
In the case of the VS
aircraft, crews can request an early left or right turn to speed up their next approach and save their (by now precious) fuel. Equally atc can request this from the crew.
So long 701, it was nice knowing you.