What is EMD in SEO?is it affect the ranking?

An EMD is a domain name that precisely matches a search query that will likely drive traffic to your website. The EMD Update — for "Exact Match Domain" — is a filter Google launched in September 2012 to prevent poor quality sites from ranking well simply because they had words that match search terms in their domain names. When a fresh EMD Update happens, sites that have improved their content may regain good rankings. New sites with poor content — or those previously missed by EMD — may get caught. In addition, "false positives" may get released.

It depends on what you are trying to do. If you are creating a blog, you need to have loads of quality content. Commercial SEO ranking is different than compared to blog or affiliate\review site.