Beyond the Screen: How Instant Messaging Works

IM clients are not as simple under the hood as they appear

From popular instant messaging programs, including WhatsApp and Yahoo Messenger, to other web-based and mobile chat applications, IM delivers billions of messages to people each day across a variety of platforms. While writing and sending these messages is instantaneous and relatively seamless, there is a lot more to it than meets the eye.

If you have ​ever wondered what it takes to connect with friends and relatives over an instant messenger, you are in the right place. This step-by-step guide explores how instant messaging works, from signing in to your favorite IM client to sending and receiving a message across the network.

Choosing an Instant Messaging Client

How Instant Messaging Works
Brandon De Hoyos

When you first set out to join an IM network, you must choose a client, a software application designed to create a connection between your computer and the network's server.

There are six types of IM clients: single-protocol, multiprotocol, web-based, enterprise, mobile app, and portable IMs. Regardless of which type you choose, they all connect the same way.

Verifying Your Account

How Instant Messaging Works
Brandon De Hoyos

Whether you connect to an instant messaging network with a client installed to your computer, to your phone or mobile device, or with a web messenger that does not require a download, the steps necessary to connect you to your contacts or buddy list are the same.

Using your computer or device's internet connection, the IM client attempts to communicate with the network's server using a protocol that tells the server specifically how to communicate with the client.

Once connected, you enter your user ID, also known as a screen name, and password to log in to the network. Screen names are typically created by users when they first sign up to join an instant messaging service. Most instant messengers are free to join.

The screen name and password information are sent to the server, which checks to ensure the account is accurate and in good standing. All of this happens in seconds.

Getting Your IM Started

How Instant Messaging Works
Brandon De Hoyos

If you are a long-time member of the instant messaging network, the server sends your buddy list data, including notifications of which contacts are signed in and available to chat.

The data sent to your computer is sent in multiple units called packets, small bits of information that leave the network server and are received by your IM client. The data is collected, organized and presented as live and offline friends on your contacts list.

From this point, the collection and distribution of information between your computer and the network's server are continuous, open and instantaneous, making the lightning-quick speed and convenience of instant messaging possible.

Sending and Receiving IMs

How Instant Messaging Works
Brandon De Hoyos

With the buddy list now open and ready for a chat, sending an instant message is a breeze. Double-clicking a contact's screen name tells the client software to produce an IM window addressed to that particular user. Input your message in the text field provided and click Enter. Your job is done.

Behind the screen, the client rapidly breaks up your message into packets, which are delivered directly to the recipient's computer or device. As you chat with your contact, the window appears identically to both parties, and messages appear within a split second of being sent.

In addition to text-based messages, you can also transmit video, audio, photos, files and other digital media quickly and directly.

If you have IM logging enabled on your client, a history of your conversation is written to files stored either directly on your computer or to the network's server. More often than not, finding IM history within the software and account files on your computer hard drive can be done with a simple search.

Signing Out

How Instant Messaging Works
Brandon De Hoyos

At some point, as the conversation wanes or you must leave your computer, you sign out of your instant messaging software. While you may be able to perform this action in two clicks, the IM client software and server go much further to ensure you no longer receive messages from friends.

Once the buddy list closes, the client directs the network server to end your connection because you have signed out of the service. The server stops any incoming data packets from being transmitted to your computer or device. The network also updates your availability to offline on the buddy lists of friends, family, and colleagues.

Incoming messages that were not received are stored as offline messages on most IM clients and are received when you sign back into the service.