Docking is carried out when ships need to moor, or to transfer personnel and materials. It involves lining up the vessels and physically connecting them. For vessels of a similar size, this connection is usually made by an extendible tunnel which forms a bridge between the airlocks of the vessels . Space stations and some ships have docking ports and bays which smaller ships can enter. For some instances, spacewalkers may be called on to assist in the process .
Docking is a delicate procedure which needs to be carried out carefully to avoid damage to the docking vessels. It can be carried out in haste during combat situations, however it takes considerable skill to do so and carries considerable risk .