If you are new to app development, you might be surprised to learn that it is possible to develop touch based app using HTML5.
Apps developed using HTML5 are the so called non-native app as it actually depends on webview to display the web pages.
Webview is part of the Android or iOS class activity. All that webview does is actually to display a web page.
For an app to access the native tools such as camera or GPS built inside a phone or tablet, most people would rely on phonegap, a framework that allow developers to wrap the app for running in Android or iPhone.