Towable or "Tow Behind"

Basic - Mounted on a Frame with Wheels

Advanced - Mounted on an actual Trailer, Purpose Built, Load Balanced with more features.

They connect via Hitches - Ball or Pintle Hooks for Larger Models.

Some Designs have a Tow Bar or Tongue which is Removable or Retractable. 

Towing Attributes:

Tongue Weight - Generally considered to be 10-15% of the Gross Trailer Weight.

Tongue Height - The ideal Tongue Height is when the Trailer is Level and the Tow Vehicle also sits Level. Adjust and Pair the Tow Vehicle's Hitch Receiver to the Level Height of the Trailer.

Tires - Trailer Tires differ from vehicle tires because they have higher load capacities, stiffer sidewalls, and are designed for heat resistance.

Break Away Parts

Chains are a Backup to connect Vehicle to the Trailer if the Hitch Parts Fail.

Electric Brake Trailers - A Breakaway Kit includes a Cable, Switch, and Battery that attaches to the Trailer Brake System; it's the secondary safety system, activating the Trailer Brakes in an emergency. The Cable (Connected to Tow Vehicle) Pulls the Switch and activates Braking in a decoupling event.