Back in 2014, Microsoft bought the developers of Minecraft, Mojang Studios. Although a lot has happened since then, Mojang Studios allowed for those who owned Minecraft: Java Edition to continue to use their Mojang account, which has been separate from the Microsoft version of the game.
Well, it is finally time for this to change. Announced on Minecraft's official website on October 21st, it looks like starting early 2021, Mojang Studios will be converting Mojang accounts into Microsoft accounts. They state that this will help with account security through Two-Factor Authentication, and it will bring all of Mojang's games under one account.
This migration will be mandatory. If you would like to continue to play the Java Edition of Minecraft, you will need to set up a Microsoft account and follow the instructions sent out in early 2021 to convert your Mojang account.
Although the Java Edition will require a Microsoft account to play, it will still be the same game. You will have access to mods and Java Edition servers just like you did before tho conversion.
To commemorate the migration, Mojang Studios said they would be giving all players who have the Java Edition of Minecraft a unique cape that can be worn in-game.
After the account migrations are complete, you will no longer be able to access your Mojang account, and new players will be unable to create Mojang accounts. This means that all games from Mojang Studios will require a Microsoft account to play.
I am shocked that it took them over six years to make this move!