There are two different types of keywords and phrases. Single keywords and what's generally known as long tail keywords. A couple of examples would be: "Articles". That would be a keyword. "Making money with articles" is known as a long tail keyword.
If you would like write articles or blog posts to promote a website or service then keywords and phrases play a very important role. Keyword density and placement are very important parts of optimizing your articles for search engines. Keywords need to be placed in your article several times, not merely once. Whenever a search engine spider sees that you've got a keyword placed several times in an article, it's going to determine that your particular article may be useful to users that do a search for that particular keyword and key phrase.
Keyword density is how often your keyword is placed in your article. Most webmasters and writers make use of a percentage to determine how many times they are going to put a keyword in an article. For example, in case you have a 500 word article and want to achieve a keyword density of 5%, then you will have to have your keyword in your article exactly 25 times. Each webmaster has their own personal density which they like to achieve based on past results. So long as you don't over optimize which is also referred to as "keyword stuffing", and you are making sufficient profit from your rankings, then you can certainly choose whatever keyword density works best for you.
Regardless of what keyword density you ultimately choose, it is very important place keywords so that you have more at the beginning and end to produce an hour glass effect. Obtaining the right keyword density in your article makes it much more likely that you will earn money from that article since it will get higher ranking in the search engine results and be seen by more people. You can find a huge selection of resources and publications dealing with keyword density, however, in the long run you will need to determine which density is more financially rewarding for your articles or blog posts.
Article Directory : http://www.articlecube.com
