KB / Getting Started / How does...work?

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Ever wonder how the Internet works? How about email? CGIs? Find out here!

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• KB / Getting Started

How does email work?

How does mail get from here to there? Here's a step by step guide to a very simple email system.

<img src="./images/illustrations/email_illustration.gif">

So you compose an email on your computer, using an email client like Outlook. You address it to someoneelse@theirdomain.com, and press Send. So what happens next? Your email program sends your mail to the SMTP server where your account is. If you are sending mail to someone else whose mail account is on that server, go to step 7. Otherwise, keep reading. The SMTP server breaks the address someonelse@theirdomain.com into two parts: someonelse (the account name) and theirdomain.com (the domain). The SMTP server then contacts a DNS (domain name service)server, and asks for the IP address where theirdomain.com is located. The DNS server sends the address back to the SMTP server. The SMTP server then sends the email message to the SMTP server where theirdomain.com is located. The second SMTP server delivers the email message to someonelse's account on the POP3 or IMAP server. Someonelse logs on to their computer and opens their email client. Their email client requests the POP3 or IMAP server to send all email from their account to their computer. If you are sending email to someone whose account resides on the same set of mail servers, the SMTP server will simply direct the mail to the local POP3 or IMAP server, where it will be delivered to the appropriate account.

How does the Internet work?

You turn on your computer, fire up your browser, and surf the web. But what's really going on here? Perhaps this article can help.

• A network is a group of computers that are connected and can communicate with one another.
• "The Internet" is a worldwide network of computers, connected by TCP/IP.
• TCP/IP is a protocol that all of the computers understand. It's an agreement about how the computers exchange information.
• All computers connected to the Internet have an IP address consisting of four numbers separated by periods (for example: 123.231.13.23).
• To make addresses easier for humans to remember, DNS (domain name service) associates domain names like www.yourdomain.com with the numeric address of the computer where that domain is hosted.
• When you type in a domain name, your computer requests web page files from the address of the computer where the files are located. These files are sent to your computer, and displayed in your browser.

This is how it works:

<img src="./images/illustrations/ftp_illustration.gif">

You build your web pages on your computer. You then upload them to your account on DreamHost's servers. [what does upload mean?] Your visitor types in your web address on their computer. This sends a request for your web page files to the computer where they are located (ie; our servers). In response, our servers send copies of your files to your visitor's computer. This makes your page appear on their screen.