What is SEO?
Search Engine Optimization, or "SEO," is the practice of increasing the quantity and quality of traffic to your website through organic search engine results, for example, in Google.
When a user submits a search query to a search engine, the search engine's algorithm determines which pages are relevant and which have authority for the keywords used.
The search engine provides results that are also based on a number of factors,such as the user’s location and search history. Site factors that influence rankings include the quality of the code (is it built with semantic html? is it accessible?) and apparent relevance of the content (presence of keywords, number of links and traffic to the site, how often does the text change, etc.)
Organic search and paid search
Every web page ranks somewhere in organic search. As most users are prone to look no further than the first page of search results for their queries, it is important to our web site pages rank high enough to be seen. With SEO, we can improve both the ranking and the user-experience of our pages in organic search.
Organizations can also pay to rank for specific search queries. We call the practice of paying for search result ranking "paid search."
The most popular example of paid search are Google Ads. Usually, you find paid search results on top or on the bottom of search result pages.
The image below shows search results for the query "Google Ad." The first mentions is an actual Google ad (paid search). This is denoted by the inclusion of the word "Ad" at the top left of the entry. The second result shown here is an organic search result.
See also: Semantic HTML