There can only be two real reasons to owning a website, selling or sharing. Obviously this is quite a bold statement to make, but hear me out. Information banks like Wikipedia, social media sites, music sites like GrooveShark and even some personal websites all share their knowledge or services to other sites, many in the hope that users will pass this knowledge on and thus drive visits to said site.
On the other end of the spectrum we have shopping sites, such Ebay or Play.com, and professional sites that offer a premium paid service or product. Both these types of sites survive and indeed thrive on people visiting and interacting with their content. With this in mind, it should be clear that doing all you can to maximise conversions through your website is a very important tactic to carry out. This is essentially the bottom line of conversion rate optimisation (CRO); testing various designs and features on individual pages to discover the ideal structure for optimised conversions.