The biggest television experiment of the summer comes to an end as America finally finds out who the "Survivor" will be tonight on CBS. No matter who wins the million dollars — Rudy, Rich, Susan or Kelly — the rules for summer television — once considered to be the wasteland of sitcom reruns — were rewritten this year with the arrival of "reality-based TV."

Shows like "Survivor" and "Big Brother" play off the success of MTV's "The Real World" and "Road Rules" by filming the real life adventures of ordinary Americans transplanted into extraordinary situations. Criticized by some as voyeuristic and invasive, reality-based TV has produced unprecedented ratings. CBS, once thought to be the least hip and youthful of the big three networks, has benefited the most from the reality shows thanks to the success of "Survivor" and "Big Brother."

Although these reality-based shows are novelties for the networks, cable stations like MTV have been relying on their success for years. For nine seasons, "The Real World" has been revealing what happens when seven 20-something strangers are picked to share one house and "find out what happens when people stop being polite and start getting real." Generating some of MTV's highest ratings, "The Real World" produced the spin-off "Road Rules" in which six similarly angst-filled college students travel the country in a Winnebago and complete adventurous missions for cash prizes.

The popularity of "The Real World" and "Road Rules" lies in their realistic portrayal of conflicts between strangers thrown together in a novel living situation. When the public grows tired with sitcoms and dramatic series, the freshness of reality TV becomes appealing: no beautiful celebrities to envy, no annoying laugh track. This summer's "reality-based TV" does the same, but with a twist: a huge cash reward for whomever outlasts all the others and wins the popularity of their fellow contestants or the television public.

"Survivor" blends the greed popularized by "Who Wants to Be A Millionaire?" with the desert island of "Gilligan's Island" and the soap opera drama of "The Real World." "Survivor" has become CBS's top show this summer, shooting to No. 1 in the ratings in just five weeks with 25 million weekly viewers. Beginning in March 2000, 16 castaways — eight men and eight women — were marooned on Pulau Tiga, a remote tropical island in the South China Sea. They were divided into two tribes, the Tagi and the Pagong, and forced to create their own society in order to survive without any modern conveniences. The survivors built shelter, gathered and caught food (rats being the most exotic fare), and took part in contests for rewards like cold beer or clean clothing. During the 39 days of "Survivor," a full camera crew followed their every move, producing a one-hour television episode for each three days of island life.

The motto of "Survivor" reveals its true competitive nature: "Outwit — outplay — outlast." All 16 contestants battled to be the last remaining on the island, the ultimate survivor who would be rewarded with $1,000,000. Every three days, the castaways formed a tribal council. At this meeting, each voted by secret ballot to send one fellow castaway home, eliminating him or her from eligibility for the money. Thus the show became a survival of the fittest, with the weakest or least-popular members eliminated by tribal councils. Mark Burnett, executive producer of "Survivor," calls the show "two parts adventure contest, eight parts surviving the peer group."

Plans for Survivor II are already in the works. Premiering in early 2001, it will be set in the Australian outback, and 50,000 hopefuls have already applied. The "docu-soap" has especially caught on with the group networks are constantly trying to attract: the 18 to 34 year-old demographic.

A "Survivor" spin-off that has brought CBS additional success is "Big Brother." The show that has been a huge hit in Germany and the Netherlands takes its name from George Orwell's novel "1984," stripping its contestants of all privacy and contact with the outside world. Ten strangers live together for three months under 24-hour surveillance. The house and yard are wired with 28 cameras and 60 microphones so that no action or conversation goes unnoticed. The house guests live in a sparse, utilitarian structure: two bedrooms, one bathroom, a kitchen, living room and small garden. The participants have to grow their own vegetables, bake their own bread, and tend a flock of chickens. They also complete weekly group projects in order to win rewards and allow the viewing audience to see them interact.

Public opinion of the house guests is a key part of the "Big Brother" concept. While the winner of both "Survivor" and "Big Brother" earns a huge cash prize ($500,000 in the case of "Big Brother"), the methods for selection are different. Unlike "Survivor," where the contestants vote each other off the island, "Big Brother" contestants nominate each other for "banishment" and then the television audience can call a 900-number to vote on who will be forced to leave. This interactive aspect gives the audience unprecedented control over the direction of the show.

What began as fun escapist summer programming has exploded into a cult-like popularity. Humans are curious by nature, and the chance to pry into someone else's life is irresistible. People get caught up in the lives of the cast members as they see private lives become public. Viewers identify with the average Americans featured on these real-life shows, and producers are pleased with not having to pay professional actors. Plus, the scenarios of these shows are enviable: an exotic living situation, attractive roommates, the allure of celebrity status. Through their attraction for younger viewers, both "Survivor" and "Big Brother" have lifted CBS to a much cooler status. These reality-based shows are purely fun in their intentions, sparking conversation about character and debate about the shows' ethics.

As fun as these shows are to watch, they have raised serious issues of privacy, decency and the future of entertainment. Critics say "Survivor" promotes selfishness, encouraging conflict between cast members in order to eliminate the weak. Cooperation and teamwork are shunned as each person sets their sights on the million dollars. "Big Brother" doesn't allow its participants a moment to themselves — every minute of their day is broadcast live on the Internet. Some call these shows voyeuristic and invasive, and wonder what rules are left for television to follow.

Another issue is the question of "reality" — how realistic can a contrived television program be? In the selection of contestants and the editing of film the producers clearly manipulate the plot line and outcome of the show. Also, many contestants enter the show seeking their 15 minutes of fame, acting outrageously or intentionally starting conflicts in order to get noticed. Thus it is hard to believe any of these living situations are truly realistic, from the trendy "Real World" mansions to the stark "Big Brother" compound.

Regardless of whether reality-based shows are actually realistic or promote good values, the ratings prove their popularity. And if one rule of television remains, it is that success will be imitated. Many new reality shows are already in the works. A popular Dutch show from the producer of "Big Brother" is "Now or Never," in which a phobic contestant is confronted with his or her worst fear. NBC wants to buy the rights to "Chains of Love," a new dating show in which a girl is chained to four men for five days, eliminating one each day until one lucky man wins cash and a date.

And even if Fox's high school documentary "American High" bombed in its first few weeks, the success and allure of reality TV indicates that many more imitators are on their way.

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