What is search engine optimization: SEO?ABSTRACTWeb sites, which index and class other web sites according to their keywords, explanations and contents and make it easier and faster to reach obtained site-search results, are called as search engines. SEO “Search Engine Optimization” is the one of the widely used technique that provides web sites fast reachable. In this work we explained required information to make a web site more indexed by search engines and considering their keywords make them first listed. KEY WORDS: SEO, Search Engine Optimization, Page Rank, Backlink, Bot, Meta Tags, Social Media. 1. Introduction Internet is a wide community including millions of users and it is also named as one of todays most important communication tools. This wide community is also known as an important customer potential for everyone who thinks about business works based on Internet environment. Internet has become new channel of the business area in the modern world in which it is not possible to reach such a wide volume by using traditional selling channels. The working method, which has changed with the Internet, has created some changes in other areas and it has also enabled companies to need Internet based marketing activities. As a result of increasing popularit-y of the Internet, a crowd, which is also named as “electronic community” was appeared. Marketers, who try to reach users in a fast and effective way with direct marketing method and also reduce customer reachingcosts, aim to reach electronic communities that have big potentials. According to com-nies, this crowd, which is also named as electronic community, is evaluated as a customer. Because of this, they try to introduce and market their companies via developed web sites. On the other hand, they also know that the most important and effective introduction and marketing way is taking part on top lists of search engines. Whereas Internet includes hundred thousands of web pages, it is better to use search engines in order to reach wanted data or information. Accordi-ng to Comscore World Metrix evaluation on April 2009, Turkey has 7th biggest Internet population in Europe and furthermore, it also has users who spend the most time on the Internet in Europe. According to the research study on July 2009, 81 percent of Internet users enter to the Internet envir-onment via search engine web pages. For instance, 80 percent of people, who want to buy car, search for a car by using search engines. According to the research study on February 2009,Google is the most widely used search engine. It is important for search engines to give response for lots of people, especially marketers.Companies, which are aware of this situation, aim to take part on the first page or first row of search engines by using Internet advertisement or more natural approach: search engine optimization (seo). Because of lower costs,“seo”is preferred rather than Internet advertisement. Because of this, such a study has been performed in order to make “seo” more popular and widespread. Search engines and their working mec-hanism were explained in the second section of this paper. In the third sect-ion, search engine optimization was explained and some information and tips about how “seo” can be performed was also given. Finally, an evaluati-on for the whole study was performed in the last section. 2. Search Engine and Its Features Search engine is some kind of software, which collects data about web sites. At this point, the collected data includes the web site URL, some keywords or keyword groups that define the content of the web site, the code structure that forms the web page and also links provided on the web site. The related collected data is indexed and stored on a database. All of t-hese operations are performed by the search engine software (crawler, spid-er, bot). Search engines use special programs, which are named as spider or bot. These programs move by using hyperlink structure of the Web. They n-avigate through web pages periodically and capture changes that have been made since last navigation. Data obtained by the related programs are stored in a very wide database system. This database is called as the index of the search engine. On the other hand, the performed operation is called as “ind-exing”. When users perform a query in order to get some data or informatio-n, the related querry is transferred to the search engine index and results are shown to users Essential competition factor among search engines is appeared during “relevant result showing, sorting” process. After determini-ng the related pages with the performed querry, they must be shown to users in a sorted list structure. At this point, search engine algorithms take an im-portant role and they try to show the most relevant results for users. Briefly, searching robots collect data about each URL and store the collected data in a database. When a user c