The new font is called San Francisco, and it replaces the previous default font of Helvetica Neue. if you also have an Apple Watch then the font may feel familiar, as it is used on that device as well. You can see a comparison of the two fonts on the Settings screens below.
If you have already updated to iOS 9, then the font that you are seeing on your iPhone is the new San Francisco font. If you haven’t updated to iOS 9, then read here to see the steps that you will need to take. Unfortunately the font that you use on your iPhone is not something that you can change, so you will be forced to use the San Francisco font once you have updated to iOS 9, and you will be using the Helvetica Neue font for versions of iOS prior to iOS 9. You can, however, make some minor adjustments to the display of text on your iPhone, such as making the text larger or bold. You can find these options on the Accessibility menu, which is located at Settings > General > Accessibility.
One additional place where the display of the font becomes noticeable is on the keyboard. The iPhone keyboard will now alternate between upper and lower case letters, based on which type of letter you are about to type. That behavior is one that you can stop, and you can learn how by following the steps here. After receiving his Bachelor’s and Master’s degrees in Computer Science he spent several years working in IT management for small businesses. However, he now works full time writing content online and creating websites. His main writing topics include iPhones, Microsoft Office, Google Apps, Android, and Photoshop, but he has also written about many other tech topics as well. Read his full bio here.