Static Dungeons are locations which can be entered through a dungeon entrance that will take you to another map (through a loading screen)*. They are designed for groups of 3-5 players. However, most of them can be done solo or duo or in larger groups with a loss of efficiency.
Open world mobs in their area are designed for solo players. As map in "Static" you may find chests there, which drop silver and sometimes items.
Map in Static Dungeon was created for group of 3-5 players. You can find Group Dungeons there, they are one tier higher than map from which you came.
Static Dungeons may be found at Royal Continent and Outlands.
All the group dungeons can be found on the region maps as a blue entrance to the cellar, but on the worldmap each type of dungeon will look differently:
*Not taking into account the outside open world dungeons around the world bosses. To take a look at that check the Raid Dungeons page.