Software updates
Latest software update
What are the changes included in the latest software update?
How do I get the latest software updates?
All you need to do is connect your iPhone to iTunes and you'll be prompted automatically to download the new software.
If I don't download the update at first can I go back to iTunes and get it later?
Yes you can.
Can I make my iPhone go back to the previous version at a later date?
Any new software that you download cannot be removed.