Some Definitions

1. Protocol

A protocol is a set of rules that govern data communication.
A protocol defines what is communicated and when it is communicated.

2. Internet

A collection of interconnected networks is called an Inter network or just Internet. A common form of internet is a collection of LAN's connected by a WAN.

3. Intranet

• An intranet is a private network that is contained with an enterprise. It may consist of many interlinked local area networks and also use leased lines in the wide area network. 
• An intranet includes connections through one or more gateway computers to the outside internet. 
• The main purpose of intranet is to share company information and computing resources among employees. 
• An intranet can also be used to facilitate working in groups and for teleconferences.