SEO is a complex practice and often misunderstood. There is a lot of misinformation and it's easy to draw the wrong conclusion, so the aim of this talk is to bust some prevalent myths and to explore some common technical issues in more detail. We'll look at some factors affecting crawling & indexing, duplication issues, canonicalization of URLs and why it matters, Google penalties, search engines' ability to handle JavaScript, and a quick look at what the Mobile First index means. Search Engine Optimization, SEO, is a collective term for all the different kinds of actions one can take to improve a web site's organic visibility and ranking in a search engine like Google. Improving a site's visibility is accomplished through a combination of efforts regarding content, linking, and technical aspects. In this session we'll focus on technical SEO. Many developers have a greater impact on a site's performance in organic search than they realize. It is much more complex than just adding titles and meta descriptions to pages, especially when working with large web sites in a competitive industry.