Measuring the number of search engines that have indexed your site is an easy way to check the website growth resulting from your SEO efforts. The more pages indexed, the easier it is to get a ranking for more keywords. The more popular and important a site is, the more links from that site matter. A site like Wikipedia has thousands of diverse sites linking to it, which means it's probably a popular and important site. Keyword research can prove to be one of the most high return activities, not only in SEO, but in search marketing as a whole. Selecting the right keywords and strategically placing them in key areas of your pages isn't rocket science, but it does take a little time and dedication. Always do your research and conduct your own experiments With very little money, you can create a website to test all types of backlinks and have your own case studies.