This document summarizes the major changes to search engine optimization that occurred in 2013. It identifies 6 major algorithm updates from Google that year, including Penguin updates that aimed to reduce low-quality links. It also discusses the rise of authorship and publisher accounts on Google+ to verify websites and content. Mobile website speed and performance became more important factors in search ranking as well. The document recommends focusing on creating high-quality, useful content for visitors and staying on top of algorithm changes.