Please Note: If you do not know the basics of HTML, you will not be in the position to understand this article completely.
SEO or Search Engine Optimization is all about making your site Search Engine friendly! If your site is search engine friendly, you will show up in search engine "search results".
And that is what you want! Because if you show up in Google search results, for example, your site will show up every time someone searches for a term that is related to your site and you will start getting a huge amount of targeted traffic from Google! So, the question is, what is the meaning of "search engine friendly"? Search engines are funny creatures.
They like certain sites and they do not like other websites.
They are a little like women.
They are hard to please and it takes time and effort to figure out why exactly they don't like you.
(Sorry all the women who are reading this.
) If you want Google and other search engines to like your website, you have to design it in a particular way so that you make it easier for the search engine to like you.
You see, when a search engine first finds your site, it wants to know what your website is all about.
If they know what your website is about then they can display it when someone is searching for the information your website provides.
So, to figure out what your website is about, they look at certain parts of your web page...
like your title, heading etc.
On seeing these things they know what your site is about so they can show your site when something related to your site is searched for.
So, when you design your website, make sure that you make it as easy as possible for the search engines to know what your website is about.
This is called "SEO", Search Engine Optimization.
There are whole companies who are dedicated to SEO and pleasing the search engines.
SEO is an art and people are studying it all over the world.
It's like a business and a game to get your website to show up on the first page of the search results at Google.
There are some very important things you must do SEO-wise while designing your website.
But before we go into them, let us go into the concept of a "keyword" What is a "keyword"? When you have a website about "hats" for example, you want your website to be the website that shows up when some one goes to Google and types "hats".
If you have a website about health and a web page about "cancer" then you want this web page of your website to show up when someone goes to Google and searches for "cancer".
This is basically a keyword.
A keyword is the word that you want your website or web page to show up in the search results for.
Search Engine Optimization is all about putting the "keywords" in the right places when designing your site.
So, when making your web pages, first decide, "What is the keyword of this web page? OR For what keyword should this web page show up in the search results?" Once you decide this, and you know the keywords for the particular web page, follow the following SEO guidelines:

• Put the keyword once in the "title" tag of the page.
  

What do I mean be "once in the title tag"? I don't mean the title will be something like: "Hats" I mean the title will be a standard title.
Like a title you would give to an article like: "Hats - The enigma!" OR "All about hats and their types!"

• Put the keyword once or twice in the "description" tag of the web page.
  (By the way, you must have unique title and description tags for all your pages.
  )

• For all your pages, the heading of the page must be done though the "H1" tag.
  The keyword must be there in the H1 tag.
  

• The file name of the web page must contain the keyword.
  For example, the keyword of a page is "lung cancer" then the file name must be "lung-cancer.
  html"

These are the basics of SEO.
And, from my experience, these are the most important aspects of SEO.
If you follow these rules for each and every page of your website after thinking about the appropriate keywords, you should be all-right! I am not saying that, just by doing these things you will start showing up in the search results.
No! What I am saying is, if you do these things, search engines will clearly understand what your website is about.
You website will be search engine friendly.
However, if you want to show up in the search results, you will have to work on "Links" and "link building".
But, that is another article for another time.
What I have mentioned above are just the "on-page" SEO factors that you must keep in mind while designing your website.
There are also off-page SEO factors, like links from other websites pointing to your website with the "keyword" in the anchor text.
But, as I said, that is another article for another time.
Please Note: In some cases, it may be so that your visitors may get confused if you use a particular "keyword" in the H1 tag etc.
In this case, DO NOT use the keyword just for SEO.
The VISITOR is more important.
The VISITOR IS MOST IMPORTANT! DON'T CONFUSE THE VISITOR.