The Challenge has been an MTV staple for decades now. This show puts former reality show contestants (originally drawing from the Real World and Road Rules casts exclusively) against each other in physical challenges and/or puzzles, all while they are trapped living in a huge, amazing house. Alliances, politics, backstabbing, hookups, fights, and general drunkenness have also been known to ensue.
What separates The Challenge from other tv shows of similar nature is that contestants often return season to season, with some contestants having been on 10+ seasons. This allows storylines to continue across years. You might watch your favorite contestant rise from 'sweet rookie underdog'to 'multi season champion' to 'veteran bully'. Not only this, but the physical challenges (especially some of the eliminations and the Final challenge) are actually incredibly grueling and require those who really want a shot at winning to specially train year-round.
I was just an elementary schooler when The Challenge began, so I literally grew up watching some of these people and continue to into my late 20s. That's not to say you wont enjoy it if you jump right into the current season without te background experience- the current seasons have drawn lots of brand new contestants from UK reality shows which has introduced a whole new set of characters and a US vs UK dynamic which has totally ushered in a brand new era of the show.
The Challenge has it all- personable characters, ridiculous personalities, great athletes, high drama, endearing underdogs, malicious bullies, and a plethora of VERY attractive people. Phenomenal television.