Two terms are often used in networking industry, when describing network protocols.
1) Proprietary Protocol 2) Standard Protocol
Proprietary protocols are usually developed by a single company for the devices (or Operating System) which they manufacture. AppleTalk is a proprietary protocol developed by Apple Inc. Appletalk protocol may work well in network environments consisting only Apple devices. But other vendors may not support Appletalk protocol. Proprietary protocols will not scale well in network environments consisting of multi-vendor equipments.
Standard protocols are agreed and accepted by whole industry. Standard protocols are not vendor specific. Standard protocols are often developed by collaborative effort of experts from different organizations.
Examples of standard protocols are IP, TCP, UDP etc. RFC (Request for Comments) is an IETF platform to develop Standard Protocols.
To understand the concept of standard protocols more clearly, take a real world example of shaving blade. A shaving blade has a globally agreed and accepted shape, so that it can fit well in a razor manufactured by different vendors.