Search spam is when you create posts just to drop back-links back to your website.
This post is a good example of search spam, I have just replied to your question and dropped a link to my site, incidentally about ranking websites and SEO.
unfortunately the links from this site are no-follow, meaning they do not pass any link juice to the target. However just including a naked URL or company name can count as a mention, meaning it still may (in terms of Googles algorithm) infer association and therefore provide some sort of prestige, if you company name (SEOpremo ltd) is mentioned on the referring site.
This is not SEO spam but just for demonstration and example purposes.
As you can see I have added a company mention AND naked URL BUT no actual hyperlink… As I mentioned they are no-follow