Dimensional Door is one of the types of doors added by Dimensional Doors for dimensional travel.
There are two methods to crafting the Dimensional Door. The first is the most expensive method using up an entire Ender Pearl for one door, the alternative takes a bit more time and effort but one Ender Pearl will yield a total of four Dimensional Doors after the creation of Stable Fabric.
When placed, if a rift does not exist in that location, one will be created leading to a 29x29x29 (293) block area that may be used by the player freely. No Monoliths, or other hostile entities may spawn in the dimension. If a rift does exist at the location placed, the door will follow the existing rift and can take the player to the location the rift is tied to.
If found in Dimensional Dungeons, Dimensional Doors will send the player one "level" deeper into the dungeon.
Dimensional Door is also the name of a technical block for Dimensional Doors. They only appear to be used when a Dimensional Door is placed and acts as the upper half of the door. The technical block cannot be obtained legitimately.