Search Engine Optimisation (SEO) is the umbrella term for all the methods you can use to ensure the visibility of your website and its content on search engine results pages (SERPs).
Building a strong site architecture and providing clear navigation will help search engines index your site quickly and easily. This will also, more importantly, provide visitors with a good experience of using your site and encourage repeat visits. It's worth considering that Google is also increasingly paying attention to user experience, including mobile optimisation and site speed.
Search engine optimization (SEO) is the art and science of getting pages to rank higher in search engines such as Google. Because search is one of the main ways in which people discover content online, ranking higher in search engines can lead to an increase in traffic to a website.