TPA
Tip: Don't move while teleporting!
Before you teleport, you must stand still for 5 seconds. This balances teleporting by not allowing a player to teleport out of a combat situation.
Sending a Teleport Request
With TPA, you can request to teleport to another player. Simply use the command /tpa <player>, where <player> is the name of another online player, and your request will be sent to them!
Timeout
If your request has not been accepted within 45 seconds, the request will timeout and become invalid.
Accepting/Denying a Teleport Request

Java Edition
On Java Edition, you can open chat and click the [ACCEPT] or [DENY] buttons to accept or deny the request.
Bedrock (Console, PC, Mobile)
On Bedrock Edition, you will have to run a command to accept or deny the request.
/tpaccept <player>to accept a request/tpdeny <player>to deny a request