Search engine optimization is critical for anybody who is operating a website, without it nobody is going to find your site. There are literally millions of web pages about every single topic you could possibly imagine and the search engines need a way to list them in a meaningful order when they return results. In order to have any chance of getting visitors to your website it needs to be listed on the first page of the search results, this requires that your site be optimized for the keyword you are targeting. Knowing how the search engines rank websites can help you to get your site listed on the first page and result in a huge number of visitors.
Broadly speaking there are two main aspects to search engine optimization, on page and off page optimization. On page optimization basically revolves around making sure that the search engines know what your website is about. The search engines obviously don't have somebody reading every page on the internet in order to determine what each website is about, they use an algorithm to do this. Often this results in websites being miscategorized as the algorithm by no means perfect. The key to on page optimization is to make sure that the keywords that you are targeting are used in the appropriate places. Far and away the most important factor in on page SEO is the title, it has to include the keywords that you are targeting. It is also important to include your keywords in the header and a couple of times on each page. The key here is to make sure that it is obvious to the search engines what your site is about.
Off page search engine optimization can be summed up in one word, back links Search engines want to provide the most relevant information when somebody runs a search. Again since they can't read every website on the internet they need a way to make this determination, and the way the do it is with back links This is simply the number of other websites that link to yours, the search engines will assume that the site with the most, best links is the most relevant for that topic. It is not strictly about getting the most back links, where they come from is also an important factor. Ideally you want to get back links from websites that on the same or similar topics as yours. The authority of the site linking to you will also be a factor, this is by and large determined by how many back links the site linking to you has.
One often overlooked factor when it comes to back links is that they need to be anchored links, that is they need to use the keyword you are targeting. The search engines will use the text that is used in the link as a way to help determine what your site is about, if the link to your site says Click Here, the search engines will rank you for the keyword phrase Click Here. This is one reason why it is a good idea to use your keywords in the title of your website, most webmasters will use your title when they link to your site.