When your website is included in the organic listings of a search engine result page, there are two important factors that will cause people to click on your listing: rank and messaging. Of course the search engine has the ultimate say in where you rank, and even what your messaging is, but you do have some control over the messaging. Often times in an organic search listing, a snippet of your meta description is included. If your meta description is what shows, it better be inviting if you want a click.
One of the beautiful things about PPC is the ability to test different messaging in ad variations. Once you find the right ad copy to generate a high click through rate, by testing different ads, you can use that copy in the meta descriptions of your webpages. By knowing what messaging causes people to click, you can increase your click through rate in organic search as well.