Teleportation is a special kind of magical transportation. If you teleport, you disappear and reappear elsewhere instantly, without moving through the intervening space. This transportation doesn’t expend movement, unless a rule tells you otherwise, and teleportation never provokes Opportunity Attacks.
When you teleport, all the equipment you’re wearing and carrying teleports with you. If you’re touching another creature when you teleport, that creature doesn’t teleport with you unless the teleportation effect says otherwise.
If the destination space of your teleportation is occupied by another creature or blocked by a solid obstacle, you instead appear in the nearest unoccupied space of your choice.
The description of a teleportation effect tells you if you must see the teleportation’s destination.
A creature transporting themselves to another location via teleportation does not interact with any of the terrain that falls within the distance teleported, therefore teleportation cannot be affected by difficult terrain. Additionally, teleportation can be used to instantly escape from restraints or a grapple without requiring a d20 Test, so long as the character is physically capable of taking the actions required to activate the Spell, Item, or Ability that grants them the ability to Teleport.
At the DM's option, because Teleportation is generally an instantaneous and magical effect, it could be ruled that movement while teleporting also allows a creature to alter its orientation in space in accordance with it's point of arrival, such as in the case of moving through an area where the directionality of Gravity is being altered by magical means. This also means that if a creature was prone when they teleported, they could arrive at their destination in a standing position, having had to spend no movement to stand.