Sencha Touch is a user interface (UI) JavaScript library, or web framework, specifically built for the Mobile Web. It can be used by Web developers to develop user interfaces for mobile web applications that look and feel like native applications on supported mobile devices. It is based on web standards such as HTML5, CSS3 and JavaScript. The goal of Sencha Touch is to facilitate quick and easy development of HTML5 based mobile apps which run on Android, iOS, Windows, Tizen and BlackBerry devices, simultaneously allowing a native look and feel to the apps.

Source: Sencha Touch – Wikipedia