The most common objective by far in the Hitman series is that of assassinating a target. The game usually allows wide freedom on how to achieve this. In some cases however, despite being listed as an objective, it might not be necessary to actually kill them. This is the case in The Setup. For a full list, see targets.
A few NPC's are targets who're simultaneously also to some extent optional, and depending on the mission, only sometimes have to die. These only appear in Invitation to a Party, Temple City Ambush, You Better Watch Out…, Flatline and End of the Road.
Often, the survival of a certain NPC is an objective. Sometimes, it works as a way to put a time limit on the mission (such as in The Murder of Crows), sometimes a character needs to be rescued from captivity (such as in Beldingford Manor), sometimes a character needs to be abducted (such as in Shaving Lenny) and sometimes, this objective solves itself unless 47 kills the VIP. In The Death of Hannelore, all civilians are VIPs. For a full list, see VIPS.
Retrieval, destruction or placement of items
Many missions require the retrieval of certain items. These can commonly be picked up and concealed, such as in Rendezvous in Rotterdam and You Better Watch Out…. In some cases, they are keys required to open important doors. In some cases, they need to be delivered to other NPC's in the mission, such as in the Codename 47 version of The Lee Hong Assassination and Find the U'Wa Tribe. Sometimes, they cannot be concealed, but can still be carried, as in Traditions of the Trade. Sometimes, very large items have to be retrieved, as is done in Tunnel Rat. Occasionally, it has to be retrieved from a computer, as in The Graveyard Shift. Some objectives need to be destroyed, such as the video surveillance in Basement Killing and the submarine in The Bjarkhov Bomb. Finally, in some cases, an object needs to be placed somewhere at the scene, such as in The Massacre at Cheung Chau Fish Restaurant or Tracking Hayamoto. It can either be given to the player at mission start, or retrieved somewhere in the level.
Almost all missions require 47 to escape from the scene. In some missions, such as Hidden Valley and Run For Your Life, this is the only objective. There are however exceptions to this, such as Gunrunner's Paradise, Redemption at Gontranno and Requiem, where the mission simply ends when all other objectives have been completed.