By john You share a folder, someone can see it but not open it. You grant them full control, and they still cannot write to it. Windows file sharing has a reputation for being maddening, and the reason is genuinely https://saborcitosrestaurant.com/ structural: there are two separate permission systems, and both must agree.
The Protocol Underneath
Windows file sharing runs on SMB, Server Message Block. When you access \\PC-NAME\Folder, your machine speaks SMB to the other computer, asking it to list, read, or write files on your behalf.
The important consequence is that you are not touching those files directly. You are asking another computer to touch them for you, and that computer decides whether to comply. That framing explains everything that follows.
The Two Layers That Cause the Confusion
Here is the crux. Windows has share permissions and NTFS permissions, and they are different systems doing similar-sounding jobs.
Share permissions control access through the network share itself, the doorway. NTFS permissions control access to the files and folders on disk, regardless of how you reached them, whether over the network or sitting at the machine.
When you connect over the network, both apply, and the effective access is the more restrictive of the two. This is the single most common source of “I gave them permission and it still doesn’t work.” Full control at the share, read-only in NTFS, means read-only. People fix one layer, see no change, and conclude Windows is broken.
Identity Is the Other Half
Permissions are granted to accounts, which raises a question people rarely think about: who does the other computer think you are?
When you connect to another PC, you authenticate as an account that machine recognises. On a home network without a domain, each PC keeps its own accounts, so your account on your laptop means nothing to the desktop unless it has a matching account. This is why network sharing between home PCs often prompts for credentials, and why “it works for me but not for them” usually comes down to identity rather than permissions.
The Network Profile Gate
One more layer sits in front of everything. Windows treats networks as Public or Private, and on Public networks it disables discovery and sharing entirely as a safety measure.
So sharing can be configured perfectly and still fail simply because the network is marked Public. That is not a bug; it is Windows refusing to expose your files on what it believes is an untrusted network.
The Takeaway
File sharing asks another computer to act on your behalf via SMB, and it decides based on two permission systems, share and NTFS, where the more restrictive wins. Add identity, since the remote machine must recognise your account, and the network profile gate, and the notorious confusion makes sense. When sharing misbehaves, check all three rather than adjusting one repeatedly.