Alliance selection is the process of the top teams choosing who they want to play with during the Playoffs of an event.
Alliance Selection Process
Alliance selection in the FIRST Robotics Competition uses a serpentine draft format. This means the team ranked 1st becomes the captain of the first alliance, and picks their first partner. After the first alliance makes their selection, the next highest remaining seeded team becomes the second alliance captain and makes their first pick. This process continues until each of the eight alliances have two teams as members. Then selection proceeds in reverse order, with alliance 8 selecting their second robot, then alliance seven, all the way to alliance one. At the world championship, there is another round of alliance selection, going from alliance one to alliance eight.
When a team is called during alliance selection, they have the option to accept or decline the invitation to join that alliance. If they decline an invitation, they cannot be selected by another alliance, and must form their own alliance. If a team declines, and does not get the opportunity to be an alliance captain, they cannot participate in the Playoffs