Using this tag you can set up your web app to have an application shortcut icon added to a device's homescreen, and have the app launch in full-screen "app mode".
iOS Safari instructions for mobile web apps
The DOCTYPE is a required preamble for HTML5 websites.
Websites using https protocol.
UTF-8 (8-bit UCS/Unicode Transformation Format) is a variable-length character encoding for Unicode. It is the preferred encoding for web pages.