How Facebook Works

Your Facebook profile is the Web page other members will see if they look you up. It gives people an idea about who you are and what your interests include. Facebook assumes that many of the people with whom you'll want to connect work for the same company, went to the same school or live in the same town as you.

To make it easier to find friends both old and new, Facebook gathers information about you and everyone else to create a dense network of contacts. The upside is that you'll be able to see old classmates or coworkers who have Facebook accounts; the downside is that everyone else in that network will be able to find you. You can choose not to answer questions or to adjust privacy settings so that others can't find you, but that tends to defeat the purpose of a social networking site. ­

Your unmodified profile has:

­If you visited another member's unmodified profile, you'd see the same fields and sections, but under his or her profile picture you'd have a few more options, including:

When you log into your account, you arrive at your personal Facebook homepage. The basic homepage layout includes a news feed that keeps you updated about what your friends and networks are up to. There's also a status update section, which contains notices about messages you've received, invitations to events, notices about applications your friends would like you to try and a place where you can tell people how you're feeling or what you're up to. There's also a link that lets you invite friends to join Facebook.

Business owners, artists, bands and public figures can make special Facebook profiles. Instead of becoming friends with the owners of these accounts, you can become a fan. If you work for a company that doesn't have a presence of Facebook, it's a good idea to discuss a strategy with others before creating an account -- most human resources departments don't care for surprises.

You can customize your Facebook profile using Facebook applications, some of which were developed by members just like yourself. In the next section, we'll learn about the rich world of Facebook applications.

Facebook's applications set it apart from other social networking sites. Facebook's first-party applications include photos, videos, groups, events, marketplace, posted items, notes and gifts. These are applications developed by Facebook and available to all members. Here's a quick breakdown on what each application does:

Facebook is always working on developing new applications for members. If you're familiar with Facebook, you know there are hundreds of other applications available on the site. Facebook didn't develop these applications -- other Facebook members did.

Many sites give users limited access to an application programming interface (API), which lets users develop applications using the host site as a platform. But for most of these sites, user applications aren't featured on the site prominently. Third-party Facebook applications can dramatically change your experience on the site, including a massive overhaul to your profile page. Your simple profile can transform into an exciting page that includes videos, product reviews, games and virtual pets. But there's also the potential for chaos -- if you activate too many applications on your profile, it will become a sprawling Web page that other members might find difficult to navigate.

In the next section, we'll take a closer look at how Facebook members can create their own applications.

To create applications in Facebook, you first must add the Facebook developer application to your profile. You also must have access to a Web server where you can store your application -- Facebook does not host third-party programs. Applications can be Web-based, desktop-based or mobile-device-based. In other words, you can create applications that take advantage of the Facebook platform but aren't incorporated into member profiles. For example, it's possible to program an application that creates a window on your desktop that is linked to your profile's news feed.

Facebook says that its application programming interface (API) is based on a Representational State Transfer (REST) interface, a term coined by Roy Fielding in his Ph.D. dissertation at the University of California, Irvine. In a REST network, form follows function. Fielding's ultimate REST network was an idealized version of the World Wide Web that had independent components that worked together to maximize the efficiency of data transfers [Source: Fielding].

In terms of Facebook's API, a REST-interface means that applications interfacing with Facebook send method calls using Hypertext Transfer Protocol (HTTP) GET or POST requests. HTTP is the communications protocol used by the World Wide Web -- the GET request retrieves information and the POST request adds information to an existing Web page. This means that Facebook applications can retrieve information from member profiles, post messages to profiles or do both.

Developers can also use the Facebook Query Language (FQL), which is similar to Structured Query Language (SQL). Query languages are programming languages designed to retrieve information from databases. With FQL, a developer can obtain information about any user who downloads his or her application. In a way, that's really what Facebook applications are all about -- gathering information about users. Developers could use this information as a way to create target audiences for advertising or build a consumer base for a particular product. Facebook has been criticized by people who believe the site allows application developers to gather data from members, including personal information and Web surfing habits.

For those developers who want to create applications that deeply integrate themselves into Facebook's platform, there's the Facebook Markup Language (FBML). Facebook derived the language from HTML and added some site-specific tags. Using this language, developers can create applications that become a more integral part of the user's Facebook experience, affecting profile appearance and function.

Every application has a space on Facebook called a canvas page, which developers can use however they wish. When a user clicks on an application icon, his or her web browser goes to that application's canvas page. Developers can include Web advertising on canvas pages, sell products using a Facebook-designed interface or simply share information with the user.

In the next section, we'll look at how you can access Facebook through a mobile device like a cell phone.

You can access Facebook features using a mobile device like a cell phone in three ways: mobile text messages, mobile uploads and mobile Web browsing. Let's take a look at each of these in turn.

Text messages use a standardized mobile text transfer method called Short Message Service (SMS) or Multimedia Messaging Service (MMS). SMS allows you to send and receive text messages to services like Web sites, voice-mail systems and e-mail servers. An SMS message can only be up to 160 characters long. The MMS standard is an improvement on SMS, with no size limit to messages (though very large messages require an advanced 3G phone network to transfer through the system). Not all phones have SMS or MMS capabilities.

When you send a text message from your phone to Facebook, the message transmits to a mobile switching center (MSC), which sends the signal to a signal transfer point (STP). From there, the message goes to a short message service center (SMSC), which then sends the text to Facebook. When Facebook sends a message to your phone, the process is reversed. Using text messages, you can look up basic member profile information, send messages (including pokes and wall posts), add friends to your network and interact with some Facebook applications.

Mobile uploads work in a similar way to text messages, but must use MMS. MMS allows you to send not only text, but also sound files, video and images. The transfer method is similar to SMS, but it requires a handheld device compatible with the MMS standard. Because some devices aren't MMS compatible, service providers sometimes build in a feature that alerts a user when he or she has received a multimedia message. The message usually tells the user to visit a Web page link to view the message.

With MMS messages sent from your phone, you can upload photos to your profile -- they'll appear in a special uploaded photos section. You can also upload notes or videos from your phone to your profile. In either case, you must create your multimedia message first, then send it to the appropriate e-mail address.

Your phone must have Web browsing capabilities in order for you to visit Facebook from it. You'll need to direct your phone's browser to m.facebook.com, Facebook's site designed specifically for mobile browsing. To upload notes to Facebook, you send the message to notes@facebook.com. For photos or videos, you send the message to mobile@facebook.com.

Unlike typical Facebook pages, the mobile counterpart's code is in Extensible HyperText Markup Language (XHTML). XHTML is a more restricted language than standard HTML. One of the reasons for this is that the World Wide Web Consortium (W3C), an international organization that develops interoperable technologies for the Web, recognized the need for a Web language that mobile devices could easily interpret. Computers have more resources than mobile devices, and can interpret much more complex Web pages than a cell phone or similar gadget. XHTML helps to level the playing field.

In the next section, we'll look at some of Facebook's impressive statistics.

While the company began as the pet project for a group of Harvard students, today it calls Palo Alto, Calif., home (the company also has an office in New York). Facebook has more than 350 employees, and the benefits package sounds pretty sweet. It includes:

Facebook's popularity continues to grow day by day. The company claims that it has more than 57 million active members -- users who have logged onto Facebook over the last 30 day period -- on the site. Since January 2007, the average number of new registrations per day is 250,000. Facebook says that the number of active users doubles every six months. Members from the United States account for most of Facebook's population, followed by members in Canada and the United Kingdom.

Facebook also claims to be the No. 1 image-sharing service on the Internet, drawing more traffic than the second-, third- and fourth- place sites combined. In terms of image numbers, this means that Facebook receives more than 14 million uploaded images every day. Because there's no limit on how many images a member can upload and new members arrive at Facebook every day, this number will likely continue to rise exponentially.

Since June 2007, when Facebook first allowed third-party developers to create applications, developers have debuted more than 7,000 programs on the Facebook platform. Every day, developers introduce another 100 applications to the site. Facebook estimates that more than 80 percent of all members have used at least one third-party application.

Because it is so popular and heavily trafficked, Facebook requires massive amounts of storage space, both in a digital and physical sense. According to one Facebook employee, the company relies on around 200 memcached servers for production (day-to-day operation of the site) and a few more for developmental purposes [source: Grimm]. "Memcached" stands for memory caching, a method of temporarily storing data. A memcached server temporarily stores information in the server's memory, reducing the need to search a database for information. This decreases the amount of time it takes between a request for information and the delivery of that data.

Facebook also uses custom-built servers for back-end operations and a monitoring system to keep track of all the servers. Servers take up space, so Facebook leases facilities from vendors for server storage. In 2007, Facebook signed an agreement with DuPont Fabros Technology (DFT) to lease 10,000 square feet of space in an Ashburn, Va., storage center [source: Data Center Knowledge].

So how does Facebook make enough money to cover its expenses? It generates some revenue by selling web advertising space, but the majority of its funding comes from private investors. According to Facebook, it has received more than $40 million in funding since it launched in 2004.

To learn more about Facebook and related topics, follow the links on the next page.