Nobody has any real idea of what dark matter is. There exist some educated guesses, such as a new class of “weakly interacting massive particles” (WIMPs) or huge agglomerations of them (“WIMPzillas”); another class of “charged undifferentiated massive particles” (CHUMPs); or very light, neutral subatomic particles called neutralinos. No dark matter particle has ever been detected, however, so these possibilities are still nothing more than educated guesses.