Yes. If you don't pay attention to the permissions, you may give apps access to more information than you'd like. Android and iOS both provide tools (in the settings) that allow you to have some control over whether an app can get or use specific types of data. An app may need to access your contacts list to add friends, or it might need to be able to use the camera to remotely deposit a check at your bank. An app might also be collect information that seems unrelated to its purpose, like a flashlight app accessing your contacts. By keeping an eye on permissions, you can see which applications are authorized to use the various sensors on your device and exercise some control.