Search Engine Optimization is altering the content of your website so that search engines such as google give it a higer ranking. An example would be to put "baseball" very often in the text of a baseball fan page.
A site's content/ articles should always be SEO-friendly. 3-5% keyword density is usually required. Hannah here, explained what keywords are. They should be generously sprinkled through out the article. Sometimes, if you'll read a bad content, you would notice the same words appearing over and over again. You might think the writer haven't heard of the term pronoun, but this is actually effective content for search engines. Of course, human readibility should never be compromised at any given time. Good content writers can turn keyword enrich articles into something interesting and natural to read.
Commercial: By the way, I'm a content writer/copywriter you can PM me anytime if you need my help
