Guild Wars 2

Hey everyone
I have been playing a mesmer the last week or so and just hit 30. I have been anxious to try a dungeon, however I hear everywhere about mesmers being important due to their Portals. I have this ability but I just dont understand the use in it and why so many people say they need it. Can someone just explain to me how this would be used effectively?

You have to know the dungeons before you can use them to any effective extent. But basically, you can use your mesmer to run past a group of enemies, stealth to break/avoid aggro, and then put down the portal to effectively allow your group to skip an entire room full of trash mobs that drop nothing and aren’t required to be killed to finish.

Basically, you just use them to save time. I think there might be a dungeon where it saves a lot of running around too (due to the layout of the dungeon), but I’m not sure. Either case, the primary goal is to save time.