At first glance, the rules of Big Brother are simple: Sixteen houseguests live together in a house with no access to the world outside--no phone, no television, no radio, nothing. They then face off in an ongoing competition to win $500,000. Weekly contests help determine the Head of Household (basically the primary mover and shaker in the game each week, who determines the two nominees for eviction) and the holder of the Golden Power of Veto (a funky medallion that allows a player to either remove him/herself or one of his/her allies "off the block," as nomination is known). Each week, a vote of the houseguests determines which nominee goes home, and which stays on to fight another week.
Having said that, the main rule to remember about Big Brother is their unofficial tagline: "Expect the unexpected." Any rule or regulation set up in the game is open to revision at any moment, usually dependent on the whims of the producers; in other words, if the pot needs to get stirred, watch for an old houseguest to suddenly return, or a surprise nomination or eviction to pop up out of nowhere.
There are also a few common types of competitions. Head of Household contests often take the form of "endurance" comps, in which the houseguests must maintain some ludicrously difficult stance or posture indefinitely while various substances are secreted upon their persons. Imagine standing outside in the cold as you are buffeted with water, all the while standing on top of a three-foot pole and clinging to a bicycle chain, and you get the idea. The other big competition type involves knowledge of the houseguests and the game itself--those with good memories tend to go far in Big Brother. Note that it rarely requires real "smarts" to win competitions, just awareness of who you live with and what they've done.
There is a fair amount of intelligence required to play Big Brother well, however. This is because the very second these people enter the house, inevitably alliances start to form, and strategies begin to play out. At its core, Big Brother is a game about manipulation--how best to convince the right people that you are looking out for their welfare as well as your own. Failing that, it's just about convincing as many people as you can that you're on their "team," and hoping they don't talk enough to each other to discover you're playing everyone against each other.
Early in the game, strategy is less important as the sheer number of bodies in the house means that a smart player can effectively sit back and watch as the more active players eliminate each other. Many Big Brother houseguests make the cardinal mistake of playing too hard, too soon. Everyone deep down knows that rampant lies and manipulation are critical to winning, but no one wants to ADMIT it. So the early "players" tend to get eliminated early as well, whether their gifts involve winning competitions left and right or just being charismatic enough to make a lot of friends and allies. At the same time, it does help to win competitions and make friends, so it's a tricky balancing act. To avoid undue attention, players will sometimes "throw" competitions, allowing others to take on leadership roles in the house so that they aren't the ones "getting their hands dirty" and deciding other peoples' fates. Down the line, eliminating the wrong player can end up hurting you when that player's friends decide they want revenge.
One popular method of elimination, invented by Big Brother 5 houseguest "Nakomis," is known as "back-dooring." In this strategy, two players are nominated, at least one of which is a decoy designed to give someone the false impression that they are "safe" for the week. During the veto competition, the Head of Household or one of his/her "teammates" will win the veto and use it to take the decoy off the block. The Head of Household then nominates whatever player he/she REALLY wanted out of the house, and that nominated player has no way to avoid being on the block. The only trick to backdooring a houseguest is that the other nominee, the second decoy who's been reassured up and down that he/she's safe, is often eliminated instead if they are perceived as being a greater threat.
By the late stages of the game, all bets are off, and players often compete openly in alliances or "teams." Others are more discreet and can effectively play several sides against each other for long periods of time. One of the most riveting aspects of Big Brother is that each season's so different, depending on the houseguests, their respective strategies, and the outcomes of each competition. You just never know what will happen; you truly must "expect the unexpected."
If you find yourself truly getting sucked into the show, you're in luck--not only are there three episodes of Big Brother to watch each week, but there's a 24-hour live feed of all the cameras in the house available for an additional fee online. Be warned: It can be unbelievably addictive to watch people you do not know sit around together in a house and stare at each other, especially when there are occasional explosive moments of strategy or arguing, some of which never make it to the airwaves on the actual show.
CBS also hosts a daily Big Brother "talk show," known as House Calls, featuring further dirt on the happenings in the house and often including past houseguests as commentators. If you're afraid of the internet, Showtime has been airing three hours of unedited live feed late each night during the past few Big Brother seasons; it's known as Big Brother After Dark.
For those with a Big Brother obsession but pesky annoyances like, you know, JOBS or something, there are a few websites where true superfans monitor the live feeds at all times and write up reports on the happenings in the house. Overall, it's easy to get addicted to Big Brother, so once you start watching, be careful--you may never want to stop.