The ultimate goal of Mobile web development is to create functional experiences for everyone, while optimizing the user experience for a multitude of devices, each with their own limitations and capabilities.
Making the entire web experience fast is important, however there are several challenges like smaller screens, limited memory and low bandwidth networks.

The web design should make the best use of available resources.
For getting the most appropriate pixel density, there are under research HTML solutions which would guide the browser to download the image size based on the screen size of the device. Currently, one can make use of JavaScript to get the same thing done.

One also needs to provide a simple and lucid navigation pattern. The small icon with three horizontal lines near the top of the page makes sure that all options are accessible without being too intrusive.
With device detection capabilities, a single website can cater to both desktop and mobile users. HTML tables and iFrames are not recommended for mobile devices, rather using an RSS feed with Ajax is better.