What protocol is used by all computer connections to the Internet?

TCP/IP , Transmission Control Protocol/Internet Protocol is used to connect all computer to the internet, which is responsible for how data is transmitted over internet hence it is also called communication protocol(Protocol means set of rules and/or procedure).TCP/IP is in layered structure which determines how information is exchanged. TCP/IP is peer to peer protocol(One end is client computer other end is server computer) which has four layers

1. Application Layers

2.Transport Layers

3.Network Layers

4.Physical Layers

Each layers has specific functions the  functioning of the layers enable the connections and exchange of data over internet.