Members can post short updates and their connections can comment on those updates. People ask questions -- both business and personal -- and get many responses.
The basic components every member has in a profile are Wall, Info, Photos and Friends. Wall is like a bulletin board hanging off a dorm door. People can post notes on your wall for your reading and responding.
Info contains whatever details you add to your profile. This includes employers, education, contact inofmration and more. Photos, of course, contains whatever photos you share. You can create photo albums to share photos of your life and events. Friends lists all your friends.
Facebook contains many third party applications that you can install to enhance the experience. Again, you can control what applications you install and don't install. You can see a list of applications in Facebook's Application Directory (http://www.facebook.com/apps/). They range from alerts and chats to fashion and messaging.
Don't be insulted if a friend chooses to ignore your application invite. With so many applications on Facebook, people can be selective about what they accept.
Messages is your Facebook email that lets you send and receive messages from others within Facebook. The advantage is that it doesn't reveal your email address. The disadvantage is that you have to go to Facebook to see it unless you set up your account to receive email notifications whenever you get a Facebook email.