The rings represent the 5 continents united by Olympism, the fundamental belief of the Olympic Movement. The white is there as at least one of those colours features on a national flag. The flags get moved to each host before it gets lost or retires. read more
The area covered by the Olympic symbol (the rings) contained in an Olympic emblem (e.g. the 2008 Games emblem) can't exceed one-third of the total area of the emblem. The Olympic symbol contained in an Olympic emblem has to appear in its entirety (no skimping on rings!) and can't be altered in any way. read more