What is Relativity?
The word '''relativity''' usually means two things in [[physics]]: * The [[principle of relativity]], which was originally thought up by [[Galileo Galilei]], and later used by [[Albert Einstein]] as one of the important [[postulate]]s (like rules) of the [[theory of relativity]]. * The [[theory]] of relativity itself, which has two parts: [[special relativity]] and [[general relativity]]. {{disambig}}