Keywords, also known as search terms, are the words or phrases that people enter into search engines to find websites about or related to that term. To attract more visitors to your page, you need to know which keywords people are using to find similar websites, and optimize your website for these keywords. If a key search phrase is not in at least one of your pages, the search engine will not rank your page highly for that phrase, therefore you are missing out on all the potential traffic the search phrase generates.
To help achieve high ranking on search engines, you need to optimize the keyword content of your web pages. There are several different areas in your webpages where keywords should be placed, not just in the META KEYWORD tag. The keywords need to be used effectively throughout the site, and good rankings can be obtained without resorting to spammy techniques, such as listing keywords at the bottom of a page in a white font on a page with a white background.
Most search engines place a large emphasis on the actual text on a web page. As a result, the way that the text on a page is constructed plays an important role in determining the way engines index your site. When building a web site it is important to ensure that your pages contain as much relevant text as possible. Search engines gather keywords from your page contents, and rank your web page based on the keyword density. Keyword density is number of times a word or phrase is counted on a web page. The keywords can appear in the page title, links, content, descriptions and headings.
The Keyword Research section of the manual explains how to use the keyword tools to build up a list of keywords to implement into your site. The keyword research step of SEO needs to be repeated regularly to ensure that your site is consistently optimized for the most popular keywords.
Basic steps in keyword research: