"Sword Art Online" (SAO) is an anime and light novel series created by Reki Kawahara. It's set in a near-future where virtual reality gaming has become incredibly advanced. Here's a synopsis of the first season, which sets the stage for the series:

In the year 2022, the highly anticipated virtual reality MMORPG (Massively Multiplayer Online Role-Playing Game) called "Sword Art Online" is released. Players eagerly dive into the immersive virtual world, but their excitement quickly turns to horror as they discover that they cannot log out of the game. The game's creator, Akihiko Kayaba, appears and reveals that they are trapped in SAO. Worse yet, if they die in the game, they will also die in the real world.

The only way for players to escape SAO is to clear all 100 floors of the game's dungeon and defeat the final boss on each level. This monumental task requires teamwork, strategy, and courage. The story follows the protagonist, Kazuto Kirigaya (known as Kirito), a skilled player who becomes one of the key figures in the struggle to escape.

As Kirito explores the virtual world of Aincrad, he befriends other players, including Asuna Yuuki, a highly skilled swordswoman. Together, they form a close bond and become determined to free themselves and the thousands of other players trapped in SAO. Along the way, they face numerous challenges, uncover the mysteries of the game, and confront powerful adversaries.

"Sword Art Online" is not just a tale of survival within a virtual world; it also explores themes of friendship, love, and the impact of virtual reality on real-life relationships. The series spans multiple arcs, each introducing new virtual worlds and challenges for Kirito and his friends to overcome.

The first season of "Sword Art Online" is known for its action-packed battles, character development, and exploration of the psychological and emotional effects of being trapped in a virtual world. It has since spawned additional seasons and spin-off series, expanding the universe and the adventures of its characters.