It's not. PPC has nothing to do with SEO. You could put keywords in PCC (so it convert higher) but it won't affect your SEO. PPC is used to attract direct visitors, not SE's visitors.
Internet advertising analysts are of the view that the PPC model will change, perhaps for the better. These are the changes predicted: * From paying per click, the advertiser will have to pay a CPA (cost per action) - that means the advertiser will have to pay only when the visitor who clicks through to his website buys something. This is manna from the heaven for any advertiser, but it has yet to be tasted. * The pay per click advertising model will be supported or even called a pay per call model. What will happen is that when the Internet world is taken over by Internet telephony and surfers surf the net wearing headphones and speakers, the pay per click (or the pay per call) ad will have a telephone icon next to it. The visitor will click on the icon and generate an enquiry and that will trigger the charge to the advertiser and set the search engine's cash register jingling. Both these are exciting changes waiting for technology to enable them. Until then, we are back to the good old PPC.
PPC and SEO are sub parts of SEM (search Engine Marketing) and thats how they are related to each other and thats all. SEO results are shown on the left hand side of the SERP and PPC results on the right or top most side as "Sponsored Links" . PPC and SEO results have no direct or indirect effect on each other's result and positioning and they both are used for attracting different kind of audience.
If you have the budget I think PPC is a great research & testing tool for your organic SEO efforts. When you are looking to expand out to a new market, even a small PPC campaign can really quickly tell you the following: • How competitive the market is • What kind of traffic can be expected from a good rank • A baseline for conversions • Keywords, keywords, keywords PPC is like driving a nimble sportscar - fast, expensive, loud and exciting - things happen NOW. Organic SEO is like taking walking down the same road. You'll take a lot longer to get there, but if you've scouted ahead you'll know the shortcuts, and in the end be a lot stronger than sitting on your butt.