Remember The Matrix where the characters could download a “software” update to give them the knowledge required to do almost anything? iOS is a bit like that. When I wanted to upload a photo to Flickr from my phone but didn’t have the capability to do so, it was no problem! I simply opened the App Store, searched for “Flickr”, installed the app and whalla! I was able to upload the photo.
When my phone was broken and needed replacing, I simply synced the old one with iTunes and then restored the phone to factory settings (erasing all data) before handing it in to T-Mobile. When I received the replacement phone, I synced it with iTunes, thereby restoring exactly the same functionality I had before.