Search engine optimisation (SEO) is the process of improving the visibility of a website within the organic results of a search engine. SEO works by search engines such as Google using a software program called a bot to crawl the web. The bot follows links within and between websites, reads the content of pages and stores the information. The information stored by the bot is called the index, and the first goal of search engine optimisation is to have a website indexed by search engines.
Once a site is indexed, it ranks within search results. At first most sites are going to rank low among these results, so the second goal of SEO is to improve this ranking. Rank is determined by importance and relevance, and the many influential factors change regularly. Search engine optimisation must therefore form an ongoing part of your digital marketing efforts. Generally speaking, factors are related to either the technical setup of your site, or the content of your pages.