One of the most popular portions of each season are initial episodes showcasing American Idol hopefuls auditioning before the panel of judges. These early episodes focus mainly on the poorest performances from contestants who often appear oblivious to their lack of star talent. These "contestants" have been selected by the preliminary panels in a negative sense, a typical combination is lack of singing ability combined with vanity regarding their "talent." Others are selected for human interest potential, the 2005 auditions featured a "cannibal" who had sampled human flesh in an anthropology class and an aspiring female prize fighter. Poor singers often face intense and humbling criticism from the judges, and especially from Cowell, who can be harsh and blunt in his rejections. Typically the judges express disgust or dismay or suppressed laughter. Some poor performances have attained notoriety on their own; these have included season two's performance of Madonna's "Like a Virgin" by Keith Beukelaer and season three's rendition of Ricky Martin's "She Bangs" by William Hung.
Contestants must be legal U.S. residents and, for the first three seasons, had to be 16 to 24 years of age. For the fourth season, the upper age limit was raised to 28 to attract more mature and diverse contestants. In early 2003, a 50-year-old college professor named Drew Cummings filed a complaint with the Equal Employment Opportunity Commission, charging the show with age discrimination because producers denied him an audition due to his age. His case was not taken up by the EEOC.
On to Hollywood
Once in Hollywood, the three judges narrow the initial field of several hundred down to a group of 24 semifinalists, divided equally between men and women, who are invited to perform in the live portions of the show. On three consecutive weeks, the male semifinalists perform only against the other men, and the women only against the other women. Each contestant performs live (in the eastern and central time zones), in primetime, a song of his or her choice, and receives critiques from the judges, who, from this point on, serve almost entirely in an advisory capacity, with little direct influence on the results.
Viewers have two hours following the broadcast of the show in their time zone to phone in votes for their favorite contestant by calling a toll-free number (viewers may also send text messages to vote). Callers are allowed to vote as many times as they like for any number of contestants. On the following night's episode the results of the nationwide vote are announced, and the bottom two vote-getters are eliminated each week. At the end of the semifinal rounds, the six men and six women who remain advance to the finals.
During the middle seasons, the semifinal round consisted of 32 semifinalists who were divided into four groups of eight. In the first season, they were 30 contestants, divided into three groups of ten. Each week for four (three for season one) weeks, one group would perform with the top two (three for season one) vote-getters from each group advancing to the finals. When all the semifinal shows had been completed, there was a wildcard phase. Each judge chose one semifinalist to advance to the final round, and a studio audience vote determined the final wildcard spot, rounding out the field of twelve finalists. In season 1, 5 contestants were chosen, and judges chose one to advance to the finals.
Semifinalists must submit to background checks and may be summarily disqualified for past behavior deemed undesirable, such as an arrest record. Several finalists have been disqualified for revelations that surfaced late in the competition.
Final twelve
In the finals, which last eleven weeks, each finalist performs a song live in primetime from a weekly theme (two songs in later rounds). Themes have included Motown, disco, big band music, and Billboard #1 hits. Some themes are based on music recorded by a particular artist, and the finalists have a chance to work with that artist in preparing their performances. Artists around whom themes have been based include Barry Manilow, Gloria Estefan, and Elton John.
When there are three finalists remaining, themes are no longer used. Instead, each contestant sings three songs: one of their own choice, one chosen by the judges, and one chosen by record executive Clive Davis. However in Season Two, in the final three, one song was chosen randomly from a bowl, with one chosen by the performer and one by the judges.
In any case, each week on the following night's live "results" episode, the contestant with the fewest votes is sent home. The bottom three vote-getters are separated from the remaining contestants. Over the course of the episode, two are revealed as being "safe" for the week, and the loser is sent home after performing one final song to end the episode. This process is repeated each week until the one remaining contestant is declared the winner.
--Wikipedia