[tomflack]

You post them in your stream, you can choose to only show your photos to people who you've friended or you can choose to post them all publicly. There is no middle ground.

You can share the photos outside of instagram on Twitter, Facebook, Posterous and via mail. People can view the images in their browser if you send them a URL or if they use a third-party website to browse photos.

It's quite flexible and a lot of fun sharing and commenting on other's photos. If you want to get more activity on your photos, you need to #tag them. Some people go overboard with obnoxious 20-30 tag posts.