Getting EXP later onFollow

I've been leveling a few classes trying to pick a job, and therefore haven't gotten past lvl 15. As such I've been soloing quests for the majority of my exp.
After doing so many quests (all kill x ys, get x loots, bring x to y), I was wondering if this is how you get experience throughout the game or if at some point you start to form up parties to kill things for exp? If so, when does getting exp turn into partying instead of questing?

For the most part, you could just gather experience from solo'ing and killing equal level monsters throughout the world. To be more effective at gathering experience you complete quests, some of them would be easier with parties as the quests may be Elite and/or areas may be too crowded for a single player to take on.

It isn't absolutely required to party in order to gain experience but it definately makes it easier in the later levels (20+).