Medal

In the multiplayer mode of Call of Duty: Black Ops II, medals are rewarded for outstanding accomplishments. These accomplishments can range from securing flags and bombs in objective game modes to getting an exceptional amount of kills in a single life. Each medal, including duplicates, provide bonus XP, which is displayed in the After Action Report at the end of the match.

Kill Medals
Kill Medals are rewarded whenever a player kills an enemy under circumstances different from a regular kill. This can include killing an enemy before they kill a teammate, awarding the Savior medal, or killing an enemy that has killed the killer before, awarding the Revenge medal. They are also rewarded with unconventional weapons and equipment, such as the Combat Axe and the Ballistic Knife.

Killstreak Medals
Killstreak Medals are rewarded for going on a killstreak (multiple kills in a single life). Scorestreaks do not contribute to this streak; only kills from weapons, the knife, lethals and tacticals are counted. Medals scale until the 31st kill, at which point each non-scorestreak kill will be rewarded with the Unstoppable medal.

Rapid Kill Medals
Rapid Kill Medals are awarded for killing multiple enemies in a certain timeframe. Unlike previous games, the timeframe to achieve these kills is much larger, and each kill extends the time to achieve the next. As with the Killstreak Medals, scorestreak kills do not contribute to this.

Scorestreak Medals
Scorestreak Medals are rewarded for getting direct kills on enemy players from scorestreaks. Due to this, it is impossible to get medals from support scorestreaks such as the UAV. Medals stack, meaning that multiple medals can be awarded from a single scorestreak. Example: a double kill from a Hunter Killer will award two Bullseye medals.

Scorestreak Destroy Medals
Scorestreak Destroy Medals are rewarded for destroying enemy scorestreaks. This can be done in a variety of ways, be it from using the FHJ-18 AA on a Counter-UAV, to using the Black Hat PDA on a Guardian. Destroy medals are visually similar to their scorestreak counterparts, but have a dark red background instead of a gold one.

Playlist Medals
Playlist Medals are rewarded in different game modes when certain parameters of obtained, such as capturing flags in Domination or defusing bombs.

Objective Medals
Objective medals offer some of the highest XP rewards in the game, incentivising objective play when applicable.

'NB: "Any objective game mode" relates to any game mode with a static objective or objective location. To this end, it does not include Kill Confirmed.'

Party Game Medals
Party Game Medals appear exclusively in the Party Games playlist. They are rewarded from various achievements, such as getting the most kills within a gun rotation in Sharpshooter, or quickly moving up a rank in Gun Game.

End of Match Medals
End of Match Medals are rewarded for finishing any public match.

Miscellaneous Medals
There are additional medals that are not rewarded for any of the above reasons, and revolve more around the metagame of stealing, sharing and hacking.

Trivia

 * The Efficiency medal is sometimes awarded despite not killing more than a single enemy with a single bullet. It sometimes give you the medal when you only kill one enemy with a single bullet.
 * Though the One Shot, One Kill medal is only rewarded to sniper rifles, Shotguns obtain their Camo through "One Hit Kills" in a similar fashion to sniper rifles. A "One Hit Kill" in this case refers to a single buckshot (or slug for the KSG) in the magazine, and for any shotgun does not award the medal.
 * As of patch 1.06, all gunstreak medals have been given a different design.