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Electronic mail, most commonly called email or e-mail since around 1993, is a method of exchanging digital messages from an author to one or more recipients. Email operates across the Internet or other computer networks. Some early email systems required the author and the recipient to both be online at the same time, in common with instant messaging. 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 connect only briefly, typically to a mail server, for as long as it takes to send or receive messages. Historically, the term ''electronic mail'' was used generically for any electronic document transmission. For example, several writers in the early 1970s used the term to describe fax document transmission.〔Ron Brown, Fax invades the mail market, (New Scientist ), Vol. 56, No. 817 (Oct., 26, 1972), pages 218–221.〕〔Herbert P. Luckett, What's News: Electronic-mail delivery gets started, (Popular Science ), Vol. 202, No. 3 (March 1973); page 85〕 As a result, it is difficult to find the first citation for the use of the term with the more specific meaning it has today. An Internet email message consists of three components, the message ''envelope'', the message ''header'', and the message ''body''. The message header contains control information, including, minimally, an originator's email address and one or more recipient addresses. Usually descriptive information is also added, such as a subject header field and a message submission date/time stamp. 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 multi-media content attachments. International email, with internationalized email addresses using UTF-8, has been standardized, but not yet widely adopted. Electronic mail predates the inception of the Internet and was in fact a crucial tool in creating it, but the history of modern, global Internet email services reaches back to the early ARPANET. Standards for encoding email messages were proposed as early as 1973 (RFC 561). Conversion from ARPANET to the Internet in the early 1980s produced the core of the current services. An email message sent in the early 1970s looks quite similar to a basic text message sent on the Internet today. Email is an information and communications technology. It uses technology to communicate a digital message over the Internet. Users use email differently, based on how they think about it. There are many software platforms available to send and receive. Popular email platforms include Gmail, Hotmail, Yahoo! Mail, Outlook, and many others.〔http://dir.yahoo.com/business_and_economy/business_to_business/communications_and_networking/internet_and_world_wide_web/email_providers/free_email/〕 Network-based email was initially exchanged on the ARPANET in extensions to the File Transfer Protocol (FTP), but is now carried by the Simple Mail Transfer Protocol (SMTP), first published as Internet standard 10 (RFC 821) in 1982. In the process of transporting email messages between systems, SMTP communicates delivery parameters using a message ''envelope'' separate from the message (header and body) itself. ==Spelling== Electronic mail has several English spelling options: * ''email'' is the most common form used online, and is required by IETF Requests for Comments and working groups〔(【引用サイトリンク】publisher=IETF ) This is suggested by the (RFC Document Style Guide )〕 and increasingly by style guides.〔(【引用サイトリンク】title=Yahoo style guide )〕〔(AP Stylebook editors share big changes ) from the American Copy Editors Society〕 This spelling also appears in most dictionaries.〔(【引用サイトリンク】title=Reference.com )〕〔Random House Unabridged Dictionary, 2006〕〔The American Heritage Dictionary of the English Language, Fourth Edition〕〔Princeton University WordNet 3.0〕〔The American Heritage Science Dictionary, 2002〕〔(【引用サイトリンク】url=http://www.merriam-webster.com/dictionary/email )〕 * ''e-mail'' has long been the form that appears most frequently in edited, published American English and British English writing as reflected in the Corpus of Contemporary American English data and style guides.〔〔 * ''mail'' was the form used in the original RFC. The service is referred to as ''mail'', and a single piece of electronic mail is called a ''message''.〔(【引用サイトリンク】title=RFC 1939 (rfc1939) – Post Office Protocol – Version 3 )〕〔(【引用サイトリンク】title=RFC 3501 (rfc3501) – Internet Message Access Protocol – version 4rev1 )〕 * ''EMail'' is a traditional form that has been used in RFCs for the "Author's Address"〔〔 and is expressly required "for historical reasons".〔(【引用サイトリンク】title=''"RFC Style Guide"'', Table of decisions on consistent usage in RFC )〕 * ''E-mail'' is sometimes used, capitalizing the initial ''E'' as in similar abbreviations like ''E-piano'', ''E-guitar'', ''A-bomb'', and ''H-bomb''.〔(【引用サイトリンク】title=Excerpt from the FAQ list of the Usenet newsgroup alt.usage.english )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Email」の詳細全文を読む スポンサード リンク
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