The major two political parties in the US are Republican and Democrat. Almost all polititians in the US belong to one or the other and align themselves on the issues along party lines. Generally speaking, Republican polititians are conservative on issues and are often referred to as the Religious Right. Democrats are referred to as "Liberals" and are more to the "Left", tending to spend more on social programs.

A historical example would be John F. Kennedy, a Democrat that started the Peace Corps. A good Republican example would be Ronald Reagan, that put in place "Trickle down economics", which gave huge tax breaks to the rich business people with the idea that they'd pass down the wealth to the poor.

When a person registers to vote in an upcoming election, they register as a Republican, Democrat, or Independant. Then when a primary election is held (which chooses the party candidate), only voters within their own party can vote for that parties candidiates to decide who will run in the general election.

Further, former President Bill Clinton was a Democrat and he firmly believed fellatio was not a sex act, nor was dipping a cigar in an interns, uh, vagina. So he did it a lot. Current Republican President Bush believes very strongly in killing lots of things. He was great at it as Governor of Texas and has flourished as US President.

In the US, the east and west coasts are generally Democratic, while the central states are Republican.