Resources on a Microsoft Windows network are called shares. A share can be a hardware device, such as a modem or a printer; it can be a storage device, such as a CD-ROM or optical drive; or a share can be a logical entity on a hard disk drive, such as a volume, a folder, a directory, or a file. The owner of the server or workstation must explicitly designate a particular resource in that machine as shared in order for other users to access it over the network.
Whenever a computer on a Microsoft Windows network shares any device or resource, that computer is considered to be a server. Peer-to-peer means that computers can function as both clients and servers at the same time.