Internet

A search engine is a software system designed to carry out web searches. It searches the World Wide Web in a systematic way for particular information specified in a textual web search query. The search results are generally presented in a line of results, often referred to as search engine results pages (SERPs). The information may be a mix of links to web pages, images, videos, and other types of files. Major search engines like Google and Bing work by crawling the web, indexing the content they find, and then using algorithms to rank and display the most relevant results for a user's query.

Step 1: Recall the history of the Internet. The precursor to the modern Internet was a project funded by the U.S. Department of Defense's Advanced Research Projects Agency (ARPA).
Step 2: Identify the network's name. This network was called the ARPANET. It was the first to implement the TCP/IP protocol suite and is widely considered the first large-scale, general-purpose computer network. NSFNET came later and formed the backbone of the Internet in the late 80s and early 90s.

Step 1: Recall the history of the World Wide Web. The World Wide Web (WWW) was invented by the British computer scientist Tim Berners-Lee.
Step 2: Pinpoint the year of invention. He proposed the idea in a paper in March 1989 while working at CERN, the European Organization for Nuclear Research. The first website went live in 1991. The year of its inception is considered 1989.

Step 1: Analyze the structure of an email address. A standard email address has the format `username@domainname`.

The `username` identifies the specific user.
The `@` symbol is a separator.
The `domainname` identifies the mail server that handles the email.

Step 2: Define protocol in this context. A protocol (like SMTP for sending, or POP3/IMAP for receiving) is a set of rules that email clients and servers use to communicate. The protocol is not part of the address itself.