The number of keywords and keyword density are both used by search engines to evaluate a web page revelancy in relation to a keyword. The keyword density seems more important than the number of keywords. However, don’t underestimate the number of keywords.

Number of keywords

The number of keywords is just the total number of times you can find a keyword in a text.

Keyword density

The density is slightly more subtle, but still easy ;-)… it is the ratio between the number of keywords and the total number of words. It measures the keyword strength in the text. If a keyword appears twice among 400 words, it is less important than if it appears once among 30 words.

Detailed example

In the following text,

Association football, commonly known as football or soccer, is a team sport played between two teams of eleven players, and it is the most popular sport in the world. Football is a ball game played on a rectangular grass or artificial turf field, with a goal at each of the short ends. The object of the game is to score by manoeuvring the ball into the opposing goal.

The keyword “football” appears 3 times in 68 words. Therefore we have 3 as the number of keywords and the keyword density equals 3/68 = 4.4%, which is relatively high.

In order to improve the keyword density, you can either increase the number of keywords or decrease the total number of words.

Let’s transform the previous text as follows,

Association football, known as football or soccer, is a sport played between two teams of eleven players, and it is the most popular sport. Football is a ball game played on a rectangular grass, with a goal at each of the short ends. The object is to score by manoeuvring the ball into the opposing goal.

The keyword “football” always appears 3 times and there is now 56 words. Therefore we have 3 as the number of keywords and the keyword density equals 3/56 = 5.3%, i.e a gain of 1.1%, which is higher. The meaning is very close to the previous one but the density is better, which improves the optimization for search engines.

As a conclusion

Search engine optimization is not an exact science. Search engines keep their algorithm secret. We are in the situation of a black box from which only experimentation can seriously tell us about. Most of the advices come from experience, observations and tests.

The number of keywords and keyword density are both valid criteria for every HTML tags : title, a/href, img/alt, h1, strong, etc… as well as for URLs. In general, a good SEO needs a number of keywords and keyword density slightly superior to the top 10 mean of the chart, for the targeted keyword. Be carefull, going too heavy is considered as spamdexing, which can affect your rank negatively.

We start today our first phase with optimizing HTML code. Before going deeper, we need to make a few reminders about HTML.

HTML, the minimum

These basics are the minimal knowledge required in HTML without which you won’t be able to optimize your web pages. If you already know HTML, you won’t learn anything new here, moreover, you could even find some volontary pedagogic approximations.

What is HTML ?

Each web page you visit over the Internet corresponds to an HTML format file that your browser (Internet Explorer, Opera, Firefox or other) receives and has to display. This file in text format (therefore human readable) describes the graphical appearance corresponding to the web page (texts, images, layout, etc…).

For example, if you go to the Amazon homepage, you can view the file your web browser received (right click + View source code in Internet Explorer). You will get the following text (HTML code) in your notepad, corresponding to the Amazon homepage.

This description is done in HTML. HTML (Hyper Text Markup Language) is a standard language based on tags (mainly for formatting). There are tags to display text, to put it in bold, to insert images, etc… Tags are always shown between rafters <name of the tag>. The formatted text is almost always framed by an opening tag and a closing tag.

For example,
In order to show the text “mp3 player” in bold, use the “b” tag (b stands for bold) as follows,

<b>mp3 player</b>

Another example, in order to display the text “sport car” in a first level heading, use the “h1” tag (h stands for heading) as follows,

<h1>sport car </h1>

Structure of an HTML page

An HTML page is divided into two parts : a head and a body. In the head, there are tags which provide general informations about the document to display. In the body, there is the document to display and its formatting defined by specific font tags.

This is the structure of an HTML page,

<HTML>
   <HEAD>
      ... Head tags -> general informations...
   </HEAD>

   <BODY>
      ... Body tags -> web page an its formatting...
   </BODY>
</HTML>

Going deeper

These are basic knowledges to understand before learning about HTML code optimization of web pages. Nevertheless, it is strongly recommended to know a bit more about HTML.

You will find great tutorials about HTML on HTML Dog (http://htmldog.com/guides/htmlbeginner/). You should learn quite quickly from there.

To go deeper in the matter, it could be interesting to read the HTML 4.01 and XHTML 1.1 standards.