SEO stands for search engine optimization. This is a process by which a website on the web world get traffic from the organic, free, natural or editorial results searched in any search engine. To understand the SEO in simpler terms, it is important to know what is included in the term. Breaking down the describing sentence, SEO means:

1. Increasing the quality of the traffic. This basically means the ability to attract customers from over the world. Say, a large number of people are flocking in to your business or website because Google tells them that you are a seller of the apple mobiles and similar products when in reality you are a simple apple fruit seller. This is also attracting traffic but not the quality traffic. SEO helps in bringing or connecting you to customers who needs the fruit apple actually. This is quality traffic attraction.
2. Organic traffic as mentioned above simply means getting traffic without really paying for it. The ads plays a very vital role in the SERPs.
3. Once the quality traffic is there for your website or business through the optimized search pages or SERPs, the quantity of traffic automatically increases.