Dock
General Overview
A Dock or Docking Port is a block which function is to connect a ship to another ship or to interact with a station.
Ship to Station Docking
Docking at AI Stations
To be able to interact with a station, you have to be "docked" at this station. For a ship to be able to dock at a station it has to be equipped with docking ports. They always come with something similar to a landing strip, so they are normally easy to find when close to a station. If your ship is close enough to the landing strip, you can active the stations tractor beams (Default [F]) to let yourself be pulled towards the dock until you are docked. This is normally slower than just flying towards the dock, but activating the tractor beam kills your velocity, so it can save you from crashing into the station. Alternatively, the transporter upgrade and transporter block can be used to avoid this docking procedure.
Docks on your own Stations
When interacting with owned stations one does not need to be docked, but can instead just fly as close as 0,3 km and interact with the station like any other owned ship. When editing a owned station, the number of docks can be seen in the stats. A owned station always needs at least two docks if there are less then docks will be spawned at the farthermost point from the center of mass. The maximum of docks a station can have is four, any additional docks will not be recognized as docking ports. Furthermore, NPCs and owned, automated ships will use those docks to trade with your stations.
Generally it does not matter which material docks are built of, because it doesn't change their stats
Ship to Ship Docking
Since the release of the Black Market DLC it is possible to use the docking block on ships, which unlocks a lot of new options.
The Basics of Docking
So the dock makes it possible to "merge" two objects together. "Objects" are ships owned by the player or neutral objects like containers and asteroids. So obviously not both objects need to have a dock, only one of them needs one. The amount of objects docked together is also not limited and it is also possible so make chains of docked objects.
To actually dock an object, you need to get close enough to the thing you want to dock. Then activate the docks tractor beams (Default [Y]) and the object will be pulled towards the dock until it is docked and thus "fused" to the ship. It can afterwards be released by pressing [Y] again, or [CTRL]+[Y] to undock all docked objects.
The strength of the tractor beams is determined by the docking block's size. The larger the dock, the stronger are the tractor beams and the farther away the object to dock may be.