1. It is a process that increases the visibility of your site in SERP.
2. It is process to increase the traffic of your site from search engine.
3. It is a process of getting traffic to a "free", "organic", "Editorial", or "natural" is listed on search engines.
4. It is a process to increase your business goal and sale.
5. It is the process of improving the volume and quality of traffic to a web site from search engines via "natural" Search.

I like the fifth one that  "It is the process of improving the volume and quality of traffic to a web site from search engines via "natural" Search."

 
All are loking approximately  right.
The true definition of Search Engine Optimization (SEO) can be stated as a highly specialized process of building a successful website. We say successful because if a commercial website cannot be found in the major search engines, it is not successful, it just isn't doing it's job.

All of them are right. Search engine optimization is one of the most important components of Internet Marketing. Each and every technique that is used in online marketing fails or succeeds on the basis of SEO. If the optimization of the website is effective than the chances are that your endeavor of marketing products and services on the internet will be successful.

Search Engine Optimization (SEO) can be stated as a highly specialized process of building a successful website. We say successful because if a commercial website cannot be found in the major search engines, it is not successful, it just isn't doing it's job.

Quote from: denniemark on November 10, 2011, 05:52:02 AM
1. It is a process that increases the visibility of your site in SERP.
2. It is process to increase the traffic of your site from search engine.
3. It is a process of getting traffic to a "free", "organic", "Editorial", or "natural" is listed on search engines.
4. It is a process to increase your business goal and sale.
5. It is the process of improving the volume and quality of traffic to a web site from search engines via "natural" Search.

SEO includes all these definitions and advantages so i like all of them.

I like third definition "It is a process of getting traffic to a "free", "organic", "Editorial", or "natural" is listed on search engines".

I like fifth definition which is It is the process of improving the volume and quality of traffic to a web site from search engines via "natural" Search. This definition defines SEO correctly and completely.