Whats the purpose of a scrum in rugby, and why are they awarded?

Question

Whats the purpose of a scrum in rugby, and why are they awarded?

Answer 1

Scrums are a way of restarting play when their is some kind of breakdown in play.  Scrums are used when something went wrong, but it wasn't dangerous or illegal play which would warrant a penalty.  

Scrums are used when there is a forward pass or a knock on.  They are also an option when a lineout throw is not straight or a kickoff goes out on the full... technical things rather than a deliberate breaking of the rules like offside, not releasing, dangerous tackles etc.

Answer 2

A scrum is a fight for the ball in certain situations. The side feeding the scrum would normally get it back.

At least rugby union takes the scrum seriously and referees make sure it is done properly, or he orders it to be re-formed.

In rugby league, the scrum is a farce with the ball being fed to the back row, and you will rarely see a scrum won against the feed.