What if you simply publish your web site and do nothing else? How would anybody know about your site? Usually among your purposes for publishing a web site is to have readers. Without readers your message doesn't get out to the world.
If you want to write articles that match the keywords people search for, then you need to know what they're searching for. That is, if you know people are looking for frobnosticators, then writing an article about frobnosticators will help the search engine match your site with those searchers. The question is, how do you find out what people are searching for.
Search Engine Optimization (SEO) is the art of making your web site have a good ranking in search engine results. Search engines tend to rank the results they give based on how close various sites match the users queries. The job the search engines fulfill, of course, is to help people find sites of interest.
Here's an idea for getting more inbound links to your web site. You can write an article and distribute it for free for others to publish. The requirement you will make is for anyone republishing your article to make a link to your site.
Google may be the 8000 pound gorilla of website marketing, and Google search results may be 80% of your traffic, and if you run Adsense advertising they may be paying most of your income, and if all that is true it makes you very dependent on Google's whims. That's the message of: Why You Should Forget About Google And Start To Diversify Your Traffic Sources Only by diversifying ones traffic sources will one be immune to whimsical changes in Google policies.
Digital cameras by their nature should be infinitely flexible. But the camera makers sell them with a given set of features. What if you want other capabilities? If the digital camera makers were the sole determiners we'd be stuck with the features they design into the cameras. Fortunately many people have worked out ways to change the capabilities of digital cameras.
The Apache web server offers a feature called "virtual hosting". What this does is make one computer be a server for more than one domain. This is a widely used way to share multiple websites on one server. For example when a web hosting company offers shared hosting, they are using virtual hosting to make it so each of their servers houses more than one of their customers.