Some sites see as much as 50% of their web traffic coming from mobile phones. It is important to have a site that displays well on small screens so your mobile visitors get the same high quality experience as everyone else.
There are many techniques to building mobile friendly sites.
An app is a program that a user installs on his or her phone and it allows them to interact with your site's database. A prime example of this type of app is the Facebook app that comes pre-installed on just about every smartphone.
Responsive Web Design
With responsive design, there is no app for users to install, they simply visit your site with their phone's browser. This technique uses new technologies which can detect the size of the screen it is being displayed on and adjust automatically to give the best results no matter what.
Separate Mobile Site
Some sites simply have 2 completely independent versions, one for normal browsers, and one for mobile browsers.
Mobile Landing Page
This is a very simple, single landing page designed specifically for phones. Typically it is just an image with links to your website, Facebook page, YouTube channel, phone number, and email address.