Err... again! Greenwich is in fact in England and on the line of the point 0, but it is not point 0. Point 0 is on the Equator (close to Africa) at point 0 East and West. Time starts there for the whole world. It has the name of "point Greenwich", because from Greenwich came first the idea on how to divide time zones (very long ago). Thanks to all for your explanations. I knew already about time zones (LOL), but what was important to know for me is where in USA is EASTERN TIME, CENTRAL TIME and if you change to summer time. I got an answer on these questions. Thanks again:-) Guitta