Yes, jQuery Mobile is only for mobile applications, which means that it will be used on different web pages on your existing desktop.
You can create a mobile site using a “responsive design,” as you mentioned, but jQuery Mobile is bigger than that, it is designed to be used for a fully dedicated mobile site.
I would look at it like this:
-If you want the webpage to look good on a desktop browser but also viewable on a mobile device, use flexible design methods such as CSS Media Queries
- If you need separate mobile pages (for example, www.mysite.com/mobile) to which mobile devices are redirected, jQuery Mobile is for you
It is also worth noting that JQM is optimized for mobile browsers by reducing the number of HTTP requests made by the server (it is important when you connect to a 3G connection, etc.), which your regular website probably does not.
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