I've tried to learn how to play bridge before, but there are so many variations (even on the Wikipedia page) that it's hard to keep track of everything and pin down exactly one way of playing it that I can use as a base to learn all the variations from.
As far as I've learned, the game is similar to (and derives from) whist, which is the most basic trick-taking game, where a team scores points for winning tricks past six. But past that, I looked at the rules for playing bridge, and couldn't make head nor tail of them. There are variations like rubber bridge and contract bridge, and among those variations on how to score points. For example, the first rulebook I ever saw bridge in had the club-trump suits worth 2 points, diamonds worth 4, etc. up to no-trump worth 10, and a team won once they scored 30 points worth of odd tricks. But then I learned from somebody else that a single trick was worth 30 points, and then from somebody else that a contract was for six plus the bid, but I didn't know what the contract was even used for and what purpose it had in scoring.
Between rubber and contract, which one is more popular? What do all the variations have in common besides their origins in whist? Please help this beginner.