If you leave your board, scooter, bike or roller skates somewhere out in the open, using a lock can be very useful in preventing theft. It would be great to just buy one lock to rule them all, but the lock you may need for your BMX is not the same lock you would need for your scooter or board.
Steel chain locks vs. Wirelocks
For bigger objects, like a bike, it is recommended to use a steel chain to wrap around the frame and an immovable object, like a street light. The thicker the chain, the better.
For smaller objects like your board, scooter or roller skates, a wirelock is what you need. The wires used in wirelocks are thinner than the chains in steel chain locks, making it possible to lock the wheels of your scooter, board or skates by letting the wire through the spokes. Wirelocks can be used to lock things together with other objects, like steel chains can, but because of the wire often being shorter than a typical chain lock, the range of objects you can lock your board, skates or scooter to is more limited. Using a wirelock in itself can also be an effective way of preventing theft. By locking the wheels alone without connecting them to an immovable object, your scooter, board or roller skates will become useless for the thief (since the wheels cannot turn) but it does not prevent the thief from moving it/them to another location.
Key lock or code lock?
Using a key lock or a code lock is mostly a matter of personal preferences, but there are some notable security differences between them. A key lock is often regarded as the safest choice, but if you have a habit of losing your keys, a code lock may be more suitable for you. If you want your code lock to be as safe as possible, it is better to choose one with the most digits in it. The more digits the code has, the less likely it is for the thief to break it.