Players can dock to other ships and board and capture them, though there are two limitations on docking.
1) The target ship must be completely disabled before it can be boarded.
2) Docking requires the attacking player to dedicate credits and slots to several gate technologies, including a docking collar and a tractor beam.
In Star Citizen, the player needs to knock down the enemy ships’ shields and then (without causing a hull breach) pick off the individual thrusters before being able to dock and board them.
Also note that docking mechanics do not apply to ships with a single crewman or certain smaller bombers; the general rule is that if there’s not room to walk around then only the salvage mechanic can apply to it. You need a crewed ship to board in the first place and you can only board crewed ships which are larger than your own (in crew size.)
Tractor Beams are a dangerous technology. They take up a standard gun slot and are designed for collecting material significantly less massive than their host ship (escaped pilots, cargo pallets, bobbleheads, etc.) As such, there’s a constant danger of overloading when using them to dock, especially with cheaper models. Additionally, they require that the target ship be absolutely disabled – firing a tractor beam at a ship that still has functional thrusters will overload it and severely damage the attacker.
A docking collar is needed to attach ships together. As with tractor beams, different levels are available which will allow connections to different sizes of ships; boarding something large like a carrier is much easier than something your own size, like a Constellation (disabling another Constellation's thrusters will require a crack shot, to say the least, and a much more accurate collar.)
Collarless external ship combat will also be added with pilots in pressure suits wearing EMUs able to battle it out in space; explosive charges would be used to open the targeted ship's airlock.
The standard VDU will not identify whether or not a ship is completely disabled; it will have a gut feel/skill element to it. Higher software upgrades will provide more in-depth scans of a target that will give you a better assurance that no maneuvering remains in place for a price.
Once a ship has successfully tractored in a target vessel, it will dock at a pre-determined location on the hull (ie, you will always dock at one of the same doors on the Constellation.) There will be a 30-second period where the attacking player cuts open the target’s door. The defender can use that time to set up to fire back.
Players will have access to a variety of upgrades to help/hinder boarding operations. Armored space suits, hand scanners, explosives, more powerful (or functionally different) weapons and so on will be available to players on both sides of the equations.
Defending players will have upgrade options that can help put the battle in their favor: a self destruct process, a dead man’s switch, automated miniguns they can position in the cockpit and so on. It’s going to be a challenge to get onboard a targeted ship successfully, one that you’ll need to work with your friends to accomplish.
Finally, the cost to recover a boarded ship will ultimately be high. Since you’ve disabled and otherwise crippled it in battle (and cut into the hull to board) you must conduct repairs in deep space if you wish to keep the hull rather than simply looting it… during which the ship is in danger of being boarded by a third party. Boarding parties should plan to carry an advance repair bot with them or to suffer the difficulty of flying in a depressurized cockpit (limited life support time, less responsive controls.) Finally, only one ship can be flown at once: you will need to work with a partner if you wish to keep a boarded ship and your own craft.