JRPass

One pass for all JR lines?

Hi there
we're thinking about getting one pass for 7 days outside of Tokyo; going to Kyoto and Osaka. I understand that there are 5 lines throughout Japan - Japan East and Japan East and so on.
Is the one JR Pass able to to be used on all JR lines...?
In other words, can we use our 7 day pass to travel East, North and West and throughout Tokyo on JR lines...?
Many thanks