As a business owner, you have a duty of care to provide a safe environment for anyone on your commercial property, and you can be found liable for failing to do so—with a couple of notable exceptions. The people who may be on your business property generally fall into three broad categories:
Invitees: If you invite someone to your business, they certainly fall into this category. But even people who aren't explicitly invited can be considered invitees. Suppose you have a retail store open for any public member to come in, look around and purchase something. In that case, they are considered invitees because there's an implicit invitation for them to enter the property during your business hours.
Licensees: This category differs from invitees, but you still have a duty of care to provide a safe environment for licensees. It includes people that you may not have been expecting but who still have a legitimate reason to be there, such as a delivery person or utility worker.
Trespassers: People who are not invited, explicitly or implicitly, and have no reason to be on your commercial property are considered trespassers, and in most cases, you have no duty of care to them. If a thief breaks into your office and hurts themselves, they generally hold you liable for that injury. There is a notable exception, however, regarding children and "attractive nuisances." If you own a motel with an outdoor pool that is not fenced off, for example, and some children break in to use the swimming pool and end up injuring themselves, you could potentially be liable because the pool is considered an attractive nuisance that is particularly appealing to children who don't always know better.
The above information means that premises liability insurance isn't limited to situations with people who are explicitly invited to be on your business property. Business owners can be considered liable for bodily injury or property damage to implicit invitees, licensees, and, in some rare situations, even trespassers.