Always lock your motorcycle or scooter. Even if you only leave him (her?) alone for a short while. Invest in a good lock, which is easy for you to use. It is cheaper than a new motorbike.
A good lock - whatever the type - is both a security barrier and a deterrent. Make the challenge as big as possible, and a lot of potential thieves will abandon.
There are many types of locks. Circumstances, personal convenience or preference will determine the choice. No lock is made for easy picking. However, combining a couple is never a bad idea.
Usually locks are mechanical, but this is now often complemented with an electronic component.
The chain or cable lock
The very definition of anti-theft, anchoring the bike to an external fixed point. Lift and go? No way. Usually rather heavy.
Disc brake locks
The most practical solution for many motorcyclists. Compact, light, easy to bring, but does not prevent your bike from being lifted.
A true classic, it consists of a massive shackle and a solid locking mechanism. Very stubborn if you don't have the key, and relatively easy to carry on the bike. Less useful if you want to anchor the bike.
This newcomer in the motorcycle world combines a number of assets of its colleagues, which is always interesting.
Floor or wall anchor
This will replace any post, bench or fence. Fix it (properly!) into the wall or floor and you'll always have an external point to anchor your bike to. Be careful though: drilling four large holes in the wall of a railway station or factory should preferably be discussed beforehand.