Besides the main questlines (main story, alliance, story, mages guild, fightersguild), you got a lot of side quests. These are often recognised as dark icons on the map. Every dark coloured icon on the map means that you have something to do there. So for example the icon for a small house on the map, will mean there is a small vilage. If you approach it you will see a questgiver and when you finish that quest (or questline), the icon will turn white on the map to indicate that you did that.

the same goes for delves (although you don't need to do a quest, to do a delve, but kill the boss inside, there is often a quest and a skyshard inside them) and public dungeons. Delves have a torch as an icon and public dungeon icons look like a cave entrance with three dots below it (not the be mistaken for a group dungeon, that one is more like a gate with square corners).

I normally try to get everything in the map white. So also dolmen (cogwheel icon indicating a group event that spawns every 15 minutes) and bosses (sometimes you need to wait for others cause they are hard to solo).The only thing that might stay black is the group dungeon.

Hello... go here: http://dulfy.net/2014/03/30/eso-quests-guide/

You're very welcome