Definition
The internet is a global system of computer networks: different networks are interconnected through the TCP/IP protocol suite and forward packets to one another, which is what carries services such as the web, email and streaming.
How it works
The internet has no single owner; it is built on common open standards. Every device has an IP address, routers forward packets hop by hop between networks, and the domain name system translates memorable names into IP addresses.
Usage
People use the internet to browse sites, send email and watch streams; for developers, “deploying to production” means making your server, in an IDC or in the cloud, reachable by the public over the internet.
Related and confusable terms
The network is the concrete system of interconnected machines; the World Wide Web is only one service running on top of the internet; “the cloud” is a way of consuming data center resources reachable over the internet — see cloud computing.