RC5-64 is a contest by RSA. Distributed net tries to find the key of a 64-bit encrypted message by checking all possible keys (brute force attack). To achieve this the keys are distributed to computers all over the work that check the keys in their idle time. 
Most people are here because they are addicted to the 
stats or because of the fun we have here. You can participate as an individual and also 
join a team if you want. There is also a $1000 price that goes to the winner and $1000 to his/her team but the possibility to find the key if you are not part of a team is almost zero. Did I say that most people are here because they ae addicted to the stats?