We've studied landing pages for quite a while, and even after compiling a lot of knowledge on the subject it can be hard to convey what actually needs to be done to your site. The guys over at kissmetrics.com have nailed it with this infographic.
We'll permalink to them - but we saved a copy of the graphic in case theirs ever comes down.. it's that good.
When we start an online marketing engagement for your business, one of the 10~ sections we'll cover is a landing page. After all the on-page optimization, and link building, and other goodies your site needs - people need a super optimized page to be sent to that drives them to perform an action. That is a landing page.
"A super-optimized page that you send visitors to which will drive them to a specific action of your choosing"