Communicating on the internet

Email uses client/server technology. If you have ever sent or received an email you have been a  part of this connection.Whether you use a piece of software designed solely for the purpose of handling email, such as Microsoft Outlook or Eudora, or a web-based client provided by a service, such as Gmail or Hotmail, the client is what lets you perform tasks such as reading and sending email messages and downloading attachments. If you are using a program like Outlook, you will need to give it information that allows it to connect to the email server that you use.

After you send the email the first step is that your email client connects to a Simple Mail Transfer Protocol (SMTP) server for your email domain (the part of your email address after the @ symbol). The SMTP server then looks at the domain of the address that the email is being sent to and queries a Domain Name System (DNS) server to ask for the IP address of the domain in question. Once it has that information, the SMTP server connects to that domain and passes the message along to its SMTP server. There are two types of incoming-mail servers: POP3 and IMAP. The biggest difference between the two is that when you get an incoming email from a POP3 server, you download it from the server onto the computer you’re using. If you get email from an IMAP server, the email stays on the server until you delete it, so you can access it from any computer you can use to log in to your server.

Instant messaging (IM) has been around since the early 1990s. It grew up as an alternative to chat rooms for people who wanted to chat in real time over the Internet. Today, instant-messaging software allows you to do a lot more than chat with other Internet users. With IM, you can send and receive files, create chat rooms, and even send messages to and from a cell phone. Before you can use IM, you must first download the client software for whatever service you want to use. Once you have the client software installed on your computer, you can run the client to have it connect to the server. Once you've connected to the server, you can log in or create a new account.