Guests expect that they will have the option to lock their bedroom or any bathroom they can access. That's why we recommend hosts add locks to any bedrooms and bathrooms that guests may use.
Guests should be able to lock the bedroom door from the inside (for their privacy) and from the outside (for the security of their belongings). A lock with a key, paired with an interior latch, is recommended.
For bathrooms that guests can access, guests should be able to lock or latch the bathroom door for privacy.
Whatever kind of lock or latch you choose, consider this:
Before you add locks, make sure to check local regulations and any other restrictions that may apply to adding locks in your space, like requirements on the kinds of locks you can add or approvals you may need.