Email, short for "electronic mail," is one of the most widely used features of the Internet, along with the web. It allows you to send and receive messages to and from anyone with an email address, anywhere in the world.
Email uses multiple protocols within the TCP/IP suite. For example, SMTP is used to send messages, while the POP or IMAP protocols are used to retrieve messages from a mail server. When you configure an email account, you must define your email address, password, and the mail servers used to send and receive messages. Fortunately, most webmail services configure your account automatically, so you only need to enter your email address and password. However, if you use an email client like Microsoft Outlook or Apple Mail, you may need to manually configure each account. Besides the email address and password, you may also have to enter the incoming and outgoing mail servers and enter the correct port numbers for each one.
The original email standard only supported plain text messages. Eventually, email evolved to support rich text with custom formatting. Today, email supports HTML, which allows emails to be formatted the same way as websites. HTML email messages can include images, links, and CSS layouts. You can also send files or "email attachments" along with messages. Most mail servers allow you to send multiple attachments with each message, but they limit the total size. In the early days of email, attachments were typically limited to one megabyte, but now many mail servers support email attachments that are 20 megabytes in size or more.