For small businesses with less than 10 PCs it's often an overkill to even have a central server, much less buy a Windows Domain Server which costs heaps of cash. However the need remains for people to share files and printers amongst their computers.
The standard solution would be to share the folders publicly. But sometimes that can be undesireable, for example if some unauthorized laptops appear in the network regularly.
Another solution is to create the same users on all computers (including setting the same passwords). This allows for authorized access, but adding new users or chaning passwords is a pain.
It would be great if it was possible to set up one of the machines as a central "user database". Other computers could then authenticate against that computer, and even set permissions on shares. Is this possible somehow?