https://www.gamespot.com/articles/monster-hunter-world-has-a-key-day-one-update-on-p/1100-6456252/

The new Monster Hunter launches for PS4 and Xbox One at the end of this week--read our Monster Hunter World review here--and like many other titles nowadays, it'll require an update on release day. Capcom recently shared details about the game's day-one patch, which adds a couple of features and will be required to play the game online.

According to the official Monster Hunter World website, the version 1.01 update will weigh in at roughly 815 MB, though the exact file size will likely vary depending on which console you're playing the game on. Most importantly, the update adds online multiplayer, event quests, chat, and other online features, meaning you won't be able to play Monster Hunter World online with other players or download any additional content until you've installed the patch.