With so many devices such as smart phones, tablets and micro laptops being used to access websites it is vital that yours looks and functions correctly on all devices. This is a problem that many designers and programmers face when designing a website, it’s easy to have a page designed on a desktop PC and think that everything looks good and works well at the testing stage but then it can throw a spanner in the works if you then try to access the website from a mobile device and find that the display is not aligned and some of the site wont function as it should.
To get round this issue a lot of larger companies have a specific web page for mobile phone access that it will automatically take you to when using your handset. Mobile sites are often more basic and have larger display text that can easily be read from a small screen, they also tend to have easier navigation around the site with not as many navigation tabs onscreen.
You may also want to have a web app that can be downloaded from the Apple or Android store for example.
Your website should be responsive and allow for changes depending on the size of the screen. Even if you have a mobile version, the desktop version should still allow for different sizes of monitors.