How do I know which quest is the "Main Quest"?

How do I know which quest is the main quest, and which are just side missions? I've reached a point where it is ambiguous of what I need to do specifically, and the galaxy map is no help.

Edit: to be more specific;

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I seem to have completed "Priority" quests, but the current "Priority" quest just tells me to do other quests while I wait. Is this how the quests play out? Priority quests just cause branching that must be completed?


The "Main Story" assignments are indeed the "Priority: X" assignments, and yes, some of them do branch.

Usually, however, this branching happens on or near the primary planet, such as the Turian Platoon on Tuchanka, or the Geth Server on Rannoch.


The Priority missions are the main quest.

If you want to see all the content, do them LAST. There are a few side quests that are not available once certain Priority missions are complete.