From the introduction:
The D&D Adventurers League is the official organized play system for Dungeons & Dragons. Players can create characters and participate in any adventure allowed as a part of the D&D Adventurers League. As characters adventure, players track those characters’ experience, treasure, and other rewards, and can take those characters through other adventures that will continue their story.
D&D Adventurers League play is broken up into storyline seasons. When players create characters, they attach those characters to a storyline season, which determines what rules they’re allowed to use to create and advance their characters. Players can continue to play their characters after the storyline season has finished, possibly participating in a second or third storyline with those same characters. A character’s level is the only limitation for adventure play. A player cannot use a character of a level higher or lower than the level range of a D&D Adventurers League adventure.
This section contains information on setting background, and on running and organizing games in the D&D Adventurers League.