How do tides work?

I understand why we have high tide etc ... but how does the tide level work ... for example why does novascotia have higher tides than new jersey ... or why does one coast of Panama have higher tides than the other coast when it is only seperated by a few miles at its closest point? Archived source: https://web.archive.org/web/20101204210606/http://www.spacetimeandtheuniverse.com/math/3838-how-do-tides-work.html