Search engine optimization /SEO/ is a set of measures and techniques that shall be applied to a website with the main purpose of ranking it as far as possible in front of the search engine keyword result (usually made by Google). 
E.g., when you ‘re searching in Google by keywords 'web site development Stara Zagora' and 'web design Stara Zagora', the present website is ranked on top of the search engine results.

Optimization is a continuous process that must start along with the initial steps of a website design in order to provide the best possible results.

Optimization should not be done for once because the website content is continuously updated, and the search engine algorithms change also.

To understand how to make good SEO, you need to know how search engines work. What are the mechanisms and algorithms for a website ranking?

The first step of optimization is the choice of keywords on the webpage (for example, about the present website I chose 'web site development Stara Zagora', 'Stara Zagora web design' and 'SEO search engine optimization Stara Zagora', and tried to use them as much as possible to improve the keywords density in this website. The keyword density can be fixed by dividing the number of keywords in the number of all words on a webpage. The size content and the keywords order are important for the search engines.

To maintain a high keywords density, while you’re increasing the content, it is often necessary to repeat more times the same words, without using synonyms, even sometimes the content does not appear to be well written. Remember, that links and images must contain the combination of keywords you have chosen.