What is SMB and how does it relate to printer sharing issues between Windows 10 and Windows 7?

SMB (Server Message Block) is a network file sharing protocol. Windows 10 primarily uses SMB3, while Windows 7 defaults to SMB1 or SMB2. SMB1 is often disabled for security reasons in Windows 10. You may need to re-enable SMB1 on the Windows 10 machine (though this is discouraged due to security vulnerabilities) or upgrade the Windows 7 machine to support SMB3.