Search Engine Optimization abbreviated as SEO and as commonly used by the average website owner involves two distinct but coordinated activities.
Technically, SEO is improving the visibility of a website in the natural, organic, non-paid Search Engine Results Pages--abbreviated as SERPs--by making sure that your website content, design, titles and descriptions are optimized so that your website ranks higher in the SERPs than a non-optimized site.
Search Engine Marketing, abbreviated as SEM, is centered upon the promotion of a website so that it becomes more visible in the SERPs through both onsite and offsite optimization strategies as well as through paid ad placements, paid inclusions, and contextual advertising.
With the recent Google algorithm changes known as Panda and Penguin, onsite optimization with a concentration on website content has become more important than ever and must work hand-in-hand with such offsite tactics as building links from other sites back to yours.
The key to better rankings in the SERPS and therefore more traffic from the search engines is offering valuable content on your website. Onsite content should be highly topical yet relatively short in length--about 400-500 words--on each specific topic.
Search engines match the content of your website to the search terms, known as keywords, that people actually use while searching for information. Rarely does a person search for a single keyword, but rather they enter a phrase that will help them narrow the results for the information they are seeking.
For example; a person is highly unlikely to enter a keyword or search term like insurance. Instead, the are more likely to enter car insurance for texas drivers 18-25 years old.
Therefore, your onsite content should include keywords similar to what people will be searching for. Don't use keywords on your site arbitrarily or indiscrimantly. That is considered keyword stuffing or keyword spam and can easily be detected by the search engines, leading to your site being penalized.
Linking strategies should recognize that not all links are not created equal. Links containing descriptive texts from the content found in the more popular or authority sites have considerably more weight and are recognized than, say, a link in your profile of a popular forum. In fact, most profile links and blog commenting spamming are usually totally ignored by the search engines and Google in particular.
Search engines love page titles. The more you can tweak the title to provide a detailed descriptions of your site content the better your results will be in the SERPs.