Today, Apple has released iOS 9. You can get the download on your iOS device via Settings > General > Software Update and then install the approximately 1 GB file via wifi.
As usual, you should back up your iOS device first via iCloud or iTunes.
Notable new apps include News which pulls articles from a wide variety of news sources and other publications.
Another nifty improvement has been made to Notes. You can now draw, take pictures and create checklists. You can even share from other apps information including maps, links, Pages documents and more. With iCloud, you can share your notes across all your devices.
Maps has been improved as well to include public transportation information in select cities.
There is even a wallet to store various credit card information to use Apple Pay to make purchases.
The iCloud Drive has been improved to store all of your files in one place. You can look for them via date, name or tags.
On your iPad, multitasking, picture in picture, slide over and keyboard commands have been improved with the new shortcut bar.
Learn more about all of these features at http://www.apple.com/ios/whats-new/.