Keywords Density
Keywords density is talking about the keywords percentage within the page content. Back in a few years ago, Yahoo allowance was 5% where is Google allowance was 3%. Any keywords with density over this amount are considered spam. However, Google search engine today is very smart, as long as the content is relevant and smooth, slightly over 3% amount will still be accepted. Focusing on single phase keywords are pointless. This kind of words hardly represent your website and not many people search single phase keywords nowadays, so SEO experts normally focus on two-phase keywords like “digital marketing”.
Backlinks
Backlinks mean other websites have referenced you url in their page. It is the most important aspect in search engine ranking. However, it is non-manipulatable and SEO experts can do nothing about this. The reason behind is that backlinks are divided into quality and non-quality backlinks, and Google only take into account for quality backlinks like New York time, Bloomberg, etc. To ask those websites to reference yours are almost impossible. SEO experts can put up your url on to forums but the effect on search engine ranking is almost negligible. So don’t waste your time on putting up url on non-quality backlinks.