These systems employ various technologies, from simple physical deterrents to complex electronic networks, to make it harder for thieves to steal a car.

Here's a breakdown of common types of anti-theft locks and how they work:

1. Immobilizers:

• How they work: This is one of the most effective and common anti-theft features in modern cars. An immobilizer is an electronic device that prevents the engine from starting unless it detects the correct, pre-programmed key or transponder. The key contains a unique code that communicates with the car's engine control unit (ECU).
  
  If the code doesn't match, the immobilizer will disable critical systems like the ignition, fuel pump, or starter motor, making it impossible to "hotwire" the car. Examples: Most modern car keys have a transponder chip embedded in them, or they are "smart keys" that wirelessly communicate with the car.

2. Alarms:

• How they work: Car alarms are designed to draw attention to a theft attempt by emitting a loud siren, flashing lights, or even sending alerts to the owner's phone. They are triggered by sensors that detect unauthorized entry (e.g., opening a door without the key), impact (e.g., breaking a window), or movement around or inside the vehicle.
  Types:
  • Passive alarms: These arm themselves automatically when the car is locked.
     
  • Active alarms: These require manual activation by the driver.

3. Physical Locks/Deterrents:

• Steering Wheel Locks: These are highly visible physical bars that attach to the steering wheel, preventing it from being turned. Even if a thief manages to start the engine, they can't steer the car.
   
• Tire/Wheel Clamps: Similar to parking enforcement clamps, these physically immobilize a wheel, making it impossible to drive the car away.
   
• Brake Locks/Pedal Locks: These devices clamp onto the brake or clutch pedal, preventing them from being depressed and thus immobilizing the vehicle.
   
• Hood Locks: Secure the vehicle's hood, preventing unauthorized access to the engine compartment where critical components might be tampered with.

4. Kill Switches:

• How they work: A kill switch is a hidden switch that, when activated, interrupts the flow of electricity to essential components of the car (like the fuel pump or ignition system), rendering it impossible to start. They can be manual or remotely controlled.

5. GPS Tracking Systems:

• How they work: While not a "lock" in the traditional sense, GPS tracking systems are a powerful anti-theft measure. If a car is stolen, these systems can provide real-time location data, allowing law enforcement to track and recover the vehicle. Many modern cars have integrated GPS tracking, or aftermarket systems can be installed.

6. Keyless Entry and Smart Keys:

• How they work: These systems use advanced encryption and rolling codes to communicate with the vehicle, ensuring that only the correct, authorized key can unlock and start the car. This makes it difficult for thieves to "clone" keys or use signal relay attacks (though Faraday bags can help protect against the latter).

7. VIN Etching:

• How it works: Permanently marking the Vehicle Identification Number (VIN) on windows and other major parts of the car makes it harder for thieves to sell the stolen vehicle or its parts, as they are easily identifiable as stolen.

Anti-theft locks and systems create multiple layers of security, aiming to deter thieves, prevent unauthorized access, detect theft attempts, and aid in vehicle recovery. Many modern cars come with sophisticated anti-theft features built-in, and additional aftermarket devices can be installed for enhanced protection.