Applications are available through Google Play either free of charge or at a cost. They can be downloaded directly on an Android device through the proprietary Play Store mobile app or by deploying the application to a device from the Google Play website. Applications exploiting hardware capabilities of a device can be targeted to users of devices with specific hardware components, such as a motion sensor (for motion-dependent games) or a front-facing camera (for online video calling). The Google Play store had over 82 billion app downloads in 2016 and has reached over 3.5 million apps published in 2017. It has been the subject of multiple issues concerning security, in which malicious software has been approved and uploaded to the store and downloaded by users, with varying degrees of severity.