SEO 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 a search engine. Search Engine Optimization is a systematic process whereby several on-site and off-site factors are worked upon to improve natural (or unpaid) ranking of a website compared to millions of competitors.
Organic SEO is done through effective use of keywords, proper back-linking and writing original and useful content. So you do not have to use paid advertising to attract traffic on your website. For a successful online business, SEO (Search Engine Optimization) is a must.