Explanation:

Docking and berthing of spacecraft is the joining of two space vehicles. This connection can be temporary, or partially permanent such as for space station modules.

Docking specifically refers to joining of two separate free-flying space vehicles.[1][2][3][4] Berthing refers to mating operations where an inactive module/vehicle is placed into the mating interface of another space vehicle by using a robotic arm.[1][3][4] Because the modern process of un-berthing needs more labor and is time-consuming, berthing operations are unsuited for rapid crew evacuations in the event of an emergency.[5]

For the first fifty years of spaceflight, the main objective of most docking and berthing missions was to transfer crew, construct or resupply a space station, or to test for such a mission (e.g. the docking between Kosmos 186 and Kosmos 188). Therefore, commonly at least one of the participating spacecraft was crewed, with a pressurized habitable volume (e.g. a space station or a lunar lander) being the target – the exceptions were a few fully uncrewed Soviet docking missions (e.g. the dockings of Kosmos 1443 and Progress 23 to an uncrewed Salyut 7 or Progress M1-5 to an uncrewed Mir). Another exception were a few missions of the crewed US Space Shuttles, like berthings of the Hubble Space Telescope (HST) during the five HST servicing missions.