Glossary - E


Electronic mail or email is a way of sending, delivering and receiving messages over electronic communication systems. The term email address is used for the Internet email system based on SMTP (Simple Mail Transfer Protocol) and for intranet systems that allow users to send each other messages within one company or organization.

Internet email messages consist of two main parts:

  • Header – contains the message subject, sender, recipient and other information about the email
  • Body – contains the message itself and, usually at the end of the block, the signature

Most emails allow for pictures and other files to be sent as attachments.

For a message to be received successfully, each user must have an email address that identifies its electronic mailbox. It can be physically located on any server; particularly popular sites that offer free email inboxes with a web interface are,,, etc.  

An email address is not generally required for sending messages; typical examples are electronic postcards or a web interface that can send email messages without email addresses.

E-mail attachment

An email attachment is a computer file sent along with an email message. One or more files can be attached to an email message, and be sent along with it to the recipient. This is typically used as a simple method to share documents and images.

Email standards, such as MIME, don't specify any file size limits, but in practice email users will find they can't send very large files. This restriction is mainly because of the different size limits for various mailbox providers.

Email users are typically warned by their email client if an email and its attachments are suspicious, but if one in an inbox unexpectedly, it should always be considered dangerous. This is particularly true if it is sent by an unknown or distrusted source.

Email bomb

An email bomb is a form of network abuse by sending enormous amounts of emails to an address in an attempt to overflow the mailbox or overwhelm the mail server where the email address is hosted in what is called a denial-of-service attack.

Email spoofing

Email spoofing is a fraudulent email activity in which parts of the email header and the sender address are modified, appearing as if the email was sent from another source. This technique is commonly used for spamming and phishing to conceal the origin of an email message. By altering certain properties of the email header, such as the From, Return-Path and Reply-To fields, fraudulent users can make the email appear to have been sent from someone other than the real sender.

Sometimes the source of the spam email is indicated in the Reply-To field. If the initial email is replied to, it will be delivered to the address specified in the Reply-To field, which might be the spammer's address. But most spam emails, especially malevolent ones carrying a trojan or virus, or those advertising a website, falsify this email address, sending the reply to another potential victim.


An emoticon is a graphical symbol that consists of punctuation and special characters to express the writer’s mood, attitude, or emotions. It is a form of ASCII art, where the meaning can be more easily interpreted after the graphic is rotated 90 degrees clockwise. Emoticons are used primarily in media such as Internet chats, IRC, and SMS, though sometimes they appear elsewhere (i.e., they are slowly beginning to appear in regular journals, mostly aimed at youth interests). They are not common in official communication; however, since the mid-1990s, some writers have used them in books about programming. Because the Internet and text communications are a relatively new kind of communication, many users are still subconsciously accustomed to seeing a face or at least hearing the voice of another person. The biggest problem with electronic communication arises when the meaning of an expression (which may conceal ambiguity) cannot be understood, because it is impossible to determine the emotional state of the communicator. From a socio-psychological perspective, the creation of emoticons was predictable.

Basic emoticons:

  • :-) – smile
  • :-)) or :-D or XD – horselaugh
  • ;-) – joke (laugh with wink)
  • :-( – frown
  • :,-(  or :'( – cry
  • :-P – protruding tongue
  • :-o – wow
  • :-O – panic
  • :-| – neutral
  • o:) – angel
  • >:) – devil
  • :-/ – dissatisfied
  • :-X – quiet

Japanese emoticons (a.k.a. linear smilies) are inspired by the art of manga. Nearly all are based on a stylized representation of emotion, and were developed and used over the years in manga. For example:

  • ^.^   or  ^_^  - smile, fancy
  • ^_^;   - shy situation
  • ^_~  or  ^_-   - wink
  • O.o  or  o.O  or  O_o  or  o_O   - wow
  • ^_^//    - applause
  • T_T   - cry, sad
  • O_O   - really?


EULA (End User License Agreement) is a software license that defines what users can and cannot do with the program, such as the number of installations permitted or the terms of distribution. Even if the source code for the software is open source, the resulting product may include a EULA that prohibits editing and redistribution of the program (i.e., Mozilla® Firefox®). The user has the choice of accepting or rejecting the EULA, however the installation of the software is conditional to the user accepting the agreement by clicking the button labeled “accept.”


An exploit is a portion of software, data, or string of commands that take advantage of a computer bug, glitch or vulnerability disrupting normal behavior on computer software, hardware or other electronic device. Usually this includes seizing control of a user's computer system or attacks that allow privilege escalation or a denial of service.

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