If you hear a network acronym with a P in it, it probably stands for Protocol.
A protocol is a set of standards and rules for managing data on a network. Using a protocol can be compared to speaking a common language. I doesn't matter what hardware or software you're using. If all the parts can speak the same language and follow the same rules, they should be able to work together.
Some protocols you may have heard of:
IP - Internet protocol. This protocol governs how data gets broken up onto packets for transmission. And an IP address tells everyone on the network where your data comes from and needs to go. Often preceded by...
TCP - Transfer Control Protocol. This protocol allows two locations on the network to transmit data and makes sure the packets arrive in the correct order.
HTTP - HyperText Transfer Protocol. Runs on top of TCP/IP. Extends the capability of TCP/IP by standardizing how various types of media are moved across the web.