Any visitors who wish to search for any sort of information will use search engines. By using that visitors will find list of search engine results pages based on the keywords entered. The listings can be Paid or Organic one. Paid Advertisements are those advertisements, which appear along side, or above search engine results pages. It's a paid service. While organic listings are those advertisements listed purely based on search engine algorithms. To achieve organic listings, SEO (Search Engine Optimization) is required.
Achieving higher rankings by organic search is less expensive then getting through paid listings. Cost for paid listings are based on CPC (Cost Per Click), timeframe and keyword popularity. Site owners would more prefer to go for organic listings rather than paid listing because of cost factor.
Also, idea behind site optimization varies to as per need. Some site owner would like to have more traffic despite of visitors need while some would like to be ranked better than their competitors in the market and increase the presence in search engines. This approach proves vital as it generate inquires and helps in getting more leads. Thus, helps in getting better leads conversion rate and lifts the business to new heights.