A variety of factors go into making something SEO friendly. To get the good SEO friendly effects you need to pick the right keywords (or keyword phrases), include all sorts of hidden gems in your content, ensure that your website is fast enough to load quickly, have enough pages on your site for search engines to crawl through, use alt tags with plenty of keywords, do not have too many ads on the page, use only plain text links, do not over-optimize pages for search etc. all this leads to SEO friendly content.