When using a trailer, there are lots of additional rules of the road that you need to adhere to. From making sure that your trailer is roadworthy, which can be anything from replacing parts that are faulty with new ones from somewhere like this trailer parts provider auto and trailer, to ensuring that your vehicle is able to pull a trailer of the weight that you have (if you are unsure about this you can find this information in your cars handbook).
Something else that it is important to be aware of when you are towing a trailer is braking them. Braking a trailer means putting brake lights on them, as well as a brake which is similar to a handbrake in the car. This means that the vehicles behind you can see when you brake, as the brake lights on your vehicle will be obscured by the trailer.
To do this, brake lights are applied to the trailer which is then mechanically linked to the car and of course the electrical systems in the car via a connection that runs through the tow bar. If the gross weight of the trailer is less than 750kg, then it is not required by law to have brakes, but if it does you must ensure that these are in good working order, as you would with your car.
Although it is not always illegal to not put brakes on your trailer, it is best practice to do so as it does improve the road safety for you and other road users.