Got beaten to the explanation while I wrote this essay, but anyway...


Major expansions of the game are indicated by whole numbers:

1.0 = the now-unplayable original release of FFXIV
2.0 = A Realm Reborn
3.0 = Heavensward
4.0 = Stormblood
5.0 = Shadowbringers


Expansions are released every two years, and the time between major expansions is filled with patches every three months, adding more to the story and also new battles and gameplay elements. These are referred to with decimal-point numbers, and don't raise the level of the MSQ, so you'll get a long run of quests at Level 50 (and again at 60 and 70).

So once you reach the end of ARR and watch the end credits, you won't be straight into Heavensward, but in the story added in patch 2.1, and will have to work your way through the five 2.X patches first – but in practical terms, you're just following the MSQ the same as you always have.

Every so often you'll get a scene where characters say something like "you've earned a rest, we'll let you know if anything comes up" and you'll get an achievement notification – this indicates the end of a patch, and what would have been a three-month wait until the next quest, but now you can just pick it up straight away. (Though if you want to catch up on job quests or other optional quests without breaking the flow of the main story, this is a good time to do it.)




The other thing you'll find once you clear ARR is that a lot of new sidequests pop up to unlock optional dungeons or quests, which can feel a bit overwhelming – originally these were released two or three at a time with each patch, but now you get them all at once.

The first example you'll see of this is that after the ARR credits and returning to the Waking Sands, Minfilia will have a choice of two quests for you. "A Recurring Problem" would have been the only quest available if you were playing the game immediately after release, and then three months later you would collect the 2.1 MSQ quest "The Price of Principles". Now both quests are available at once, and you can pick them both up at the same time – but the cutscenes might seem a bit odd played one after another, because they weren't designed to be seen like that.

(Definitely pick up the 'optional' Recurring Problem quest though, because a bit later in the MSQ it won't let you continue until you've finished the three "hard mode" primal battles that it unlocks.)




Patches are more important when you're at max level, because new stronger equipment get released each time and you have to upgrade it. But for older content you'll be able to go straight to buying the top-level gear (Ironworks for ARR, Shire for HW, Scaevan for SB), and the 'patch quests' for previous expansions (ARR and HW currently) will also reward you with not-top-level gear directly. Make sure to upgrade as soon as you can, because occasionally you'll get locked out of some climactic fights if your item level isn't high enough.