The "large network of networks" is commonly referred to as the Internet.

The Internet is a global system of interconnected computer networks that uses the standardized Internet Protocol Suite (TCP/IP) to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks of local to global scope, linked by a broad array of electronic, wireless, and optical networking technologies.

The Internet carries a vast range of information resources and services, such as the World Wide Web (WWW), email, file sharing, telephony, and online gaming.

Here's a little more about the internet:

• World Wide Web (WWW): A system of interlinked hypertext documents accessed via the Internet. Source
• Email: A method of exchanging digital messages across the Internet.
• File Sharing: The practice of distributing or providing access to digitally stored information.
• TCP/IP: The fundamental communication protocols that govern how data is transmitted over the Internet. Source