Pay-per-click can be a valuable tool when used in conjunction with an organic SEO campaign. On DaniWeb, we rely on organic SEO for all our longtail traffic to all of our forum threads. This is where the majority of our ad revenue comes from. However, we then rely on Google AdWords to direct visitors to our homepage and proper landing pages (which are mostly navigational pages, so Google doesn't send traffic to these pages.) These are the pages that encourage the most amount of new signups and repeat visitors.
PPC is one kind of advertising method which be helpful for advertise for our business through text ads or banner like. It stands for pay per click and it helps to get the more traffic to your site by click on your business site ad.