Spamming is the use of messaging systems to send multiple unsolicited messages (spam) to large numbers of recipients for the purpose of commercial advertising, for the purpose of non-commercial proselytizing, for any prohibited purpose (especially the fraudulent purpose of phishing), or simply repeatedly sending the same message to the same user. While the most widely recognized form of spam is email spam, the term is applied to similar abuses in other media: instant messaging spam, Usenet newsgroup spam, Web search engine spam, spam in blogs, wiki spam, online classified ads spam, mobile phone messaging spam, Internet forum spam, junk fax transmissions, social spam, spam mobile apps, television advertising and file sharing spam. It is named after Spam, a luncheon meat, by way of a Monty Python sketch about a restaurant that has Spam in almost every dish in which vikings annoyingly sing "Spam" repeatedly.Spamming remains economically viable because advertisers have no operating costs beyond the management of their mailing lists, servers, infrastructures, IP ranges, and domain names, and it is difficult to hold senders accountable for their mass mailings. The costs, such as lost productivity and fraud, are borne by the public and by Internet service providers, which have added extra capacity to cope with the volume. Spamming has been the subject of legislation in many jurisdictions.A person who creates spam is called a spammer.

Electronic mail (email or e-mail) is a method of exchanging messages ("mail") between people using electronic devices. Email was thus conceived as the electronic (digital) version of, or counterpart to, mail, at a time when "mail" meant only physical mail (hence e- + mail). Email later became a ubiquitous (very widely used) communication medium, to the point that in current use, an e-mail address is often treated as a basic and necessary part of many processes in business, commerce, government, education, entertainment, and other spheres of daily life in most countries. Email is the medium, and each message sent therewith is called an email (mass/count distinction).

Email's earliest development began in the 1960s, but at first users could send e-mail only to other users of the same computer. Some systems also supported a form of instant messaging, where sender and receiver needed to be online simultaneously. The history of modern Internet email services reaches back to the early ARPANET, with standards for encoding email messages published as early as 1973 (RFC 561). An email message sent in the early 1970s is similar to a basic email sent today. Ray Tomlinson is credited as the inventor of networked email; in 1971, he developed the first system able to send mail between users on different hosts across the ARPANET, using the @ sign to link the user name with a destination server. By the mid-1970s, this was the form recognized as email. At the time, though, email, like most computing, was mostly just for "computer geeks" in certain environments, such as engineering and the sciences. During the 1980s and 1990s, use of email became common in the worlds of business management, government, universities, and defense/military industries, but much of the public did not use it yet. Starting with the advent of web browsers in the mid-1990s, use of email began to extend to the rest of the public, no longer something only for geeks in certain professions or industries. By the 2010s, webmail (the web-era form of email) had gained its ubiquitous status.

Email operates across computer networks, primarily the Internet. Today's email systems are based on a store-and-forward model. Email servers accept, forward, deliver, and store messages. Neither the users nor their computers are required to be online simultaneously; they need to connect, typically to a mail server or a webmail interface to send or receive messages or download it.

Originally an ASCII text-only communications medium, Internet email was extended by Multipurpose Internet Mail Extensions (MIME) to carry text in other character sets and multimedia content attachments. International email, with internationalized email addresses using UTF-8, is standardized but not widely adopted.