Lock-On is a targeting mechanism in the Kingdom Hearts series, present in all installments except the original Kingdom Hearts: Chain of Memories and the original Kingdom Hearts coded. While the player will automatically attack the closest available target, Lock-On allows the player to permanently target a single enemy or attackable object, typically signified by the tan targeting reticule turning blue. While locked on to an enemy or an object, the camera will automatically move to follow the target.
Lock-On is activated and deactivated by tapping 
in Kingdom Hearts and Kingdom Hearts II, tapping 
in Kingdom Hearts Re:Chain of Memories, double-tapping R in Kingdom Hearts 358/2 Days, tapping L and R at the same time in Kingdom Hearts Birth by Sleep, and tapping L and R at the same time in Kingdom Hearts 3D: Dream Drop Distance. Switching targets while in Lock-On is done by pressing or 
in Kingdom Hearts, by holding and moving the right analog stick in Kingdom Hearts II, and by tapping R in Kingdom Hearts 358/2 Days.
In a number of games, there are abilities that assist or enhance the targeting and Lock-On features. These include Scan, Range Extender, and Auto-Lock.
Scan
Scan (ライブラ Raibura, lit. "Libra") is an ability that appears in Kingdom Hearts and Kingdom Hearts Final Mix, Kingdom Hearts II and Kingdom Hearts II Final Mix, Kingdom Hearts 358/2 Days, Kingdom Hearts Birth by Sleep and Kingdom Hearts Birth by Sleep Final Mix, Kingdom Hearts coded and Kingdom Hearts Re:coded. It allows the player to view a targeted enemy's HP. In Kingdom Hearts its AP Cost is 1 and in Kingdom Hearts II its AP Cost is 2. In Kingdom Hearts 358/2 Days, Scan is found as an Ability Panel. In Kingdom Hearts Birth by Sleep it is a default ability.
While Scan is not available as an ability in Kingdom Hearts: Chain of Memories and Kingdom Hearts Re:Chain of Memories, Sora is automatically equipped with its effect.
In Kingdom Hearts Re:coded, Scan is also used to detect the backdoors that lead to System Sectors. Scan can be leveled up to LV 4 by linking more Bonus Boosters to CPUs. With each upgrade of the ability, Data-Sora's Backdoor Sensor is made more precise, and previously inaccessible backdoors are able to be found.
Learning Scan
Kingdom Hearts
- Sora learns Scan at level 9 with the Dream Rod, 12 with the Dream Shield, and 15 with the Dream Sword.
Kingdom Hearts Final Mix
- Sora learns Scan at level 9 with the Dream Sword, 15 with the Dream Rod, and 21 with the Dream Shield.
Kingdom Hearts II
- Roxas or Sora learns Scan at level 4.
- Double-Keyblade Roxas has Scan as a default ability.
- King Mickey has Scan as a default ability.
Kingdom Hearts II Final Mix
- Roxas learns Scan after defeating Axel.
- Double-Keyblade Roxas has Scan as a default ability.
- King Mickey has Scan as a default ability.
Kingdom Hearts 358/2 Days
- Scan is a clear bonus for Mission 04.
Kingdom Hearts Birth by Sleep and Kingdom Hearts Birth by Sleep Final Mix
- Scan is attached to Terra's, Ventus's, and Aqua's Quick Blitz commands at the beginning of their stories.
Kingdom Hearts Re:coded
- Data-Sora learns and levels up Scan by linking the CPU to the blue Bonus Boosters in the first, fourth, sixth and ninth sections of the Stat Matrix.
Range Extender
Range Extender (レンジアップ Renji Appu, lit. "Range Up") is an ability in Kingdom Hearts 358/2 Days. It is found as an Ability Panel. It allows you to lock onto enemies even if they are far away.
Learning Range Extender
Kingdom Hearts 358/2 Days
Range Extender can be purchased for 1200 Heart Points once Roxas is promoted to Rookie rank.
Auto-Lock
Auto-Lock (オートロックオン Ōto Rokku On, lit. "Auto Lock-On") is an ability in Kingdom Hearts 358/2 Days. It is found as an Ability Panel. It allows you to automatically lock on to available targets while attacking.
Learning Auto-Lock
Kingdom Hearts 358/2 Days
Auto-Lock can be purchased for 960 Heart Points once Roxas is promoted to Agent rank.
Etymology
Scan, often known as "Libra", is a recurring White Magic spell in the Final Fantasy series games. It allows the caster to extract information from any target to check their maximum and current HP, discover their weaknesses, immunities and stats.