Various specials shown before a season of Big Brother starts.

Big Brother 2000 was a near-exact port of the hit Netherlands (Holland) series of the same name. Every week, Housemates would nominate two fellow housemates and the two or more housemates with the most nominations were eligible for banishment. American viewers could then call a 1-900 number and cast a vote to banish a HouseGuest.

This season brings a complete reformatting of Big Brother 1. The introduction of the Head of Household (HOH). The HOH nominates two houseguests for eviction. The fellow contestants vote, and the player with the most votes is evicted. On finale night, all former houseguests returned to vote for who they think should win the grand prize.

This season brings about more changes to the Big Brother format - the introduction of the Silver and Golden Power of Vetos.

In this season's twist, ten of the thirteen houseguests are shocked to learn that they will compete alongside their exes. In addition, introduction of the Diamond Power of Veto and the sequestered Jury.

In this season's twists, there are two sets of pre-existing relationships in the house - secret twins and long lost siblings.

In this season's twist, every houseguest enters the house with a secret partner - believing they were the only pair. If both can reach the end, the winner would receive a grand prize of $1,000,000 and the runner-up, $250,000.

Fourteen of the best and most iconic Big Brother Houseguests make their return to compete for the $500,000 grand prize.

In the season's twists, 3 houseguests are shocked to learn their "enemy" will be entering the game - ex best friends, ex-boyfriends, and an estranged father and daughter.

In the season's twist, every houseguest would compete, be nominated, and be evicted as couples.

In the twist of the summer, three Dynamic Duos of iconic previous houseguests make their return for another chance to win - Dick and Daniele, Jordan and Jeff, Rachel and Brendon.

In the season's twist, four previous houseguests return as Coaches to build a Big Brother dream team - a $100,000 prize awaits the coach who picks the Big Brother winner.

This season's twist brings about the Battle of Block - two HOHs, 4 nominations, and the chance of an HOH being evicted.

This season brings back the iconic Twin Twist with two sisters swapping out every few days, unbeknownist to the other houseguests. The Battle of the Block makes it return.

Season 19's new twist is called “Summer of Temptation,” where the Houseguests will be challenged like never before as they embark on a season of tempting offers that could give them money, power and safety in the game. But, they will need to be careful, because for every temptation taken, there will be a consequence to face. This season's house reflects the temptation twist with words like Money and Revenge hanging on the wall, constantly reminding the Houseguests that the game never stops.

Sixteen former Houseguests return to the game for a second chance at the grand prize of $500,000.

It is the Summer of the BB Multiverse. Three former Houseguests enter the house and unleash four universes onto the house. The Comic, Humili, Scary, and Scramble-verses unlock new twists and themed competition.

This season is the Summer of Artificial Intelligence. A.I. bots Ainsley and Jankie take over and introduce a brand new competion that changes the game - the A.I. Arena.

This season is the Summer of Mystery as the Houseguests enter the Hotel Mystère, a place where secrets lurk behind every door and nothing is as it seems. This season celebrates the 25-year anniversary of the series as a whole.