What is search engine optimization?

Search engine optimization is designing, writing, coding, and programming your entire website so that there is a good chance that your web pages will appear at the top of search engine queries for your selected keywords and key phrases. Search engine optimization is optimizing for people who use search engines, NOT optimizing for search engines only.
http://WizardofSEO.com

The fundamental building blocks of a search engine optimization are:
• Keyword Research
• A user-friendly site navigation scheme and URL structure that search engines can crawl
• Objective, third party link development
• SEO mostly applies to HTML-coded pages specifically but can include other types such images, local searches, videos, mobile, and news searches.

At the core of optimization is keyword research. In order to obtain search engine visibility, you must use words and phrases that your target audience is typing into search queries. Keyword phrases must be carefully selected and placed strategically throughout your site. These keyword phrases must appear somewhat frequently and prominently on your web pages.
Optimization also involves, allowing search engines to easy access to your keyword-rich content. That can be done by creating a search-engine friendly website.
Remember, search engine optimization is part art, part science. An expert SEO professional has both technical and creative skills.