protocols - Definition from the Hotspot Shield Glossary
A protocol in computing is a set of rules that end points in a network or telecommunications connection use when transferring data or communicating. Protocols define how a piece of data should be identified, packaged and transferred and there are protocols that operate at different levels of the OSI model from data interchange to application levels.
Many protocols will be established as industry standards and have extensive documentation. In order for a protocol to work, both devices must understand and recognize it. Examples of common protocols include HTTP (Hypertext Transfer Protocol), FTP (File Transfer Protocol), IP (Internet Protocol), SMTP (Simple Mail Transfer Protocol) and DHCP (Dynamic Host Configuration Protocol).