There are hundreds of people in a rugby team, but only a dozen or so are allowed on the field at any one time. They swap places quite a lot during a match, to make sure the referee is paying attention, or come on to replace team-mates who have been killed in action.
There are two teams, and they proceed in a somewhat similar manner to football teams - at least, they have a goal each and are allowed to score points by kicking the slightly ball-like object at it but, unlike football, they can get a lot more points by driving the ball several feet into the ground behind the goal line, closely followed by themselves and several hundredweight of flying turf.
At first glance, it appears that they can get hold of the ball and convey it towards their goal by just about any means they like but this is not, in fact, the case. It is okay to win possession of the ball by wrestling a member of the opposing team to the ground and nicking it, but there are 657 angles and directions from which you may not jump on him, and huge lists of bits of him that you may not grab, depending on whether the rest of the team are standing up or lying down groaning at the time, and on which side of what line they are doing it. This means that, when a player launches himself at 70mph toward the man he is tackling, he has to do a large amount of geometric calculations whilst flying through the air before he can work out which bit of his opponent he is allowed to bash with which bit of himself.
There is always the option of getting the ball by hurling your entire team on top of the opponent, so that you all end up in a heap and it's totally impossible for the referee to tell when you grab your opponent's nadgers and twist them until he lets go of the ball, whether or not you have done so from a legal angle, on the right side of a hypothetical line between the ball and the tea tent. If you do go in for this tactic, it is then obligatory to work the ball backwards so that in emerges from between the thighs of your hindmost team-mate in a fashion reminiscent of laying an egg.
Another popular method of progressing is to form up the whole team into a credible impression of a Chinese dragon and advancing in such a manner that no heads, hands or balls are visible, and then collapsing unexpectedly in a heap and yelling 'try!'
The two manoeuvres above are called 'mucks' and 'rawls' and you have to be very careful that you know which one you're in because in one you aren't allowed to use your hands and in the other one you aren't allowed to use your feet.
If you break any of the 4975 rules, the referee is allowed to make you all line up, bend over and bang your heads together until you say sorry. This is called a 'scrum'.
In the six nations, the points are totted up in a very odd way, so that you can only win if the team you played last Tuesday wins by precisely 26 points against the team you're playing next Thursday and things like that, but as well as the main tournament, there are lots of different prizes you can win - some of which can ONLY be won by certain teams, no matter who wins the tournament. For example, if you are England, you can win the Calcutta Cup by beating Scotland and vice versa but if you're Wales, you can't win it not no-how. Ner. If you're British, you can win the Triple Crown by beating all the other British teams, and if you're Italian you can win what looks to me like a petrified bicycle tyre by beating France, and any team which manages to get through the entire tournament without winning any of those things wins a wooden spoon.
Anyway, it's jolly good fun (except if you're one of the ones that ends up in hospital). I expect the more seasoned supporters who are at present having fun by groaning, crying and threatening to murder their favourite players will be able to explain any of the finer points I may have missed.