IPhone OS 2 available to the iPhone and iPod Touch. Prior to the public release of iPhone OS 2.0, Apple held a keynote event to announce the iPhone OS Software Development Kit ("SDK") to developers. The most notable feature of iPhone OS 2 was the App Store. Before this feature was introduced, the only way to install custom applications on the device was via jailbreaking, which is strongly discouraged and unsupported by Apple. There were 500 applications available for download at the launch of the App Store, though this amount has grown dramatically since then. Now, the App Store has more than 2
IPod Touch to the iPod Touch as "training wheels for the iPhone". All iPods lack Touch ID, 3D Touch, NFC, GPS, an earpiece speaker and a noise-cancelling microphone. Depending on the generation, the iPod Touch may have a smaller or inferior display and camera(s). Newer models (5th and 6th generation) lack the ambient light sensor that makes automatic brightness available. Older models lack a built in speaker, a microphone, a camera, and a flash. No iPod Touch has a modem through which it can place phone calls or send SMS and MMS. However, 5th and 6th generation models can either piggy-back on