Most websites are meant to attract people and let them know about a brand, business or entity. Their real value is proportional to the volume of visitors in general. In other words the more people visit your website the more value your site represents. Hence, it is imperative to take the necessary actions in order to reach as large target audience as possible.
Search engine results pages (SERPs) enable people to look for a specific online content by entering subject-related keywords in their searching box. They are responsible for finding as well as listing websites with matching content. The list order is generated by complex algorithms and it depends on multiple ranking factors. See these ingredients on the picture attached.
The acronym SEO stands for Search Engine Optimization. It is the process of maximizing the number of visitors to a particular website by ensuring that the site appears high on the list of results returned by search engines.