How do I know which quest is a main one and which one is a side quest?

[Mr.Aight]

In borderlands 2 the main quest has a different icon also if you are looking at it, it says story mission.

[BondageSpider]

They didn't put a special icon on them in this game. You just have to pay attention to the story.

Long story short: Dr. Zed's mission chain eventually leads you to Sledge and your first key fragment, he unlocks the path to the Dahl Headlands, then do some missions for Lucky there to beat Mad Mel and unlock the path to New Haven, then Helena Pierce in New Haven sends you to Patricia Tannis so she can examine your key fragment. Patricia Tannis gives you the rest of your story missions up to the end, mostly related to finding more Vault Key fragments. (Some of her missions send you to talk to other people, do their missions, and eventually return back to her.)

The final missions of the game are to rescue Patricia Tannis from the Crimson Lance, and beat Commandant Steele and her troops to the Vault before they can open it.

[BloodNinJA]

as you progress through the game, the main story fleshes itself out, and you should know what is what. Just do all the side qs too, there are some nice rewards from them.

[BondageSpider]

Doing as many side missions as you can manage is a good idea, as you may be under-leveled for the story missions otherwise.

For example, don't do "Bone Head's Theft" in the beginning zone until you've done every other mission available up to that point. At the earliest possible level you get this mission, it is impossible to beat Bone Head unless a higher level team-mate kills him for you.

[Astro_80 (WASH YOUR HANDS!)]

Story missions have the Vault symbol icon. Side-missions have the cog icon.

[Moldavia]

Originally posted by Astro_80:

Story missions have the Vault symbol icon. Side-missions have the cog icon.

This is in BL2 not BL1. BL1 has nothing but a ? in the log for quests you are on and checkmarks for completed quests underneath. I just play whatever quests I am best suited for by level and listen/read everything that comes up and piece the story together on my own it is not that hard really.

[Astro_80 (WASH YOUR HANDS!)]

Originally posted by Moldavia:

Originally posted by Astro_80:

Story missions have the Vault symbol icon. Side-missions have the cog icon.

This is in BL2 not BL1. BL1 has nothing but a ? in the log for quests you are on and checkmarks for completed quests underneath. I just play whatever quests I am best suited for by level and listen/read everything that comes up and piece the story together on my own it is not that hard really.

Yep, wrong game.

[BondageSpider]

Originally posted by Astro_80:

Originally posted by Moldavia:

This is in BL2 not BL1. BL1 has nothing but a ? in the log for quests you are on and checkmarks for completed quests underneath. I just play whatever quests I am best suited for by level and listen/read everything that comes up and piece the story together on my own it is not that hard really.

Yep, wrong game.

This meme isn't funny but it's hilarious that people keep falling for it.

#MoreLikeBordermemes

[old_one_15]

Back to the original question, the quest tracker defaults to the current story mission anytime you turn in a completed mission.