All the websites which run on the desktop computers and laptops, those can also be opened and accessed on the mobile devices too, since the browser on the devices, such as: Desktop, Laptop and Mobiles; understand html code and all websites come to the browsers as a series of html codes and then browsers use those html codes to show those particular websites with the browser.
But whenever we say mobile websites, we are meaning its size, because if the websites which are opened with the desktop and laptop computers, if we open those same websites on your mobile device, then those websites will be definitely opened and run but due to its large size, it will not fit into your mobile device's small screen and you have to do scroll the page a lot. And there is also an another thing which we also need to keep in mind that, most of the mobile device's processors are much slower than our desktop and laptop computers, so the websites run on desktop and laptop computers, may run a bit slow on your mobile device.
So whenever we are making mobile websites(better to say: mobile optimized websites), we need to careful about two things: 1) Its size(size of its each page), 2) Its loading speed. So if we can careful about these two things, then we can use any technology and languages(such as: HTML, PHP, ASP.Net, Java, Flash) to make mobile friendly websites.
Thanks.Parthibansk, if this helps please login to Mark As Answer. | Alert Moderator