Short answers, pulled from the story.
The Dungeons & Dragons alignment system was first released in 1974 when Gary Gygax published the original rulebook. This initial version featured a simple three-part choice of lawful, chaotic, or neutral without a moral dimension. The system did not include the good versus evil axis until 1976.
Dungeons & Dragons 5th Edition uses a nine-point grid consisting of lawful good, neutral good, chaotic good, lawful neutral, true neutral, chaotic neutral, lawful evil, neutral evil, and chaotic evil. The system also includes an unaligned option for creatures that operate on instinct rather than moral decision-making. This grid allows for a wide range of character archetypes from noble paladins to ruthless assassins.
Dungeons & Dragons 4th Edition released in 2008 reduced the number of alignments to five: lawful good, good, evil, chaotic evil, and unaligned. This edition de-emphasized alignment and removed traditional racial stereotypes to allow for more characters with unknown or shifting motives. The system returned to nine alignments in the 5th Edition released in 2014.
Preassigned alignments for player and monster races were removed starting with the publication of Icewind Dale: Rime of the Frostmaiden in 2020 and Tasha's Cauldron of Everything in 2020. Official errata in December 2021 removed suggested alignments for playable races in 5th Edition sourcebooks. The 2022 sourcebook Mordenkainen Presents: Monsters of the Multiverse removed preassigned alignments for creatures except for specifically named characters.
Gary Gygax created the original Dungeons & Dragons alignment system when he released the first rulebook in 1974. Gygax drew inspiration from the fantasy novels of Michael Moorcock and Poul Anderson to translate philosophical conflicts into a mechanical system. The system evolved over time to include the good versus evil axis in 1976 and the nine-point grid that is standard today.