Perhaps you’re confused about what SEO is exactly and how it differs from web design. After all, isn’t a web page all you need — then you tell people about it, Google “crawls” it, and you’re all set? Well yes, at the most basic level that is probably true. But the whole “build it and they will come” mentality is fatally flawed. Here’s why.
Search engines crawl the web looking for new content and websites all the time. They don’t do this completely randomly though, but hop around to sites that it knows changes a lot first and finds links from those sites that direct it to new sites and so on and so forth. That is why it is important to list your wonderful new website with many popular, high traffic’d sites. This makes sure that Google will see your site in a quick fashion.
Once Google get there, though, you don’t want it to take a look around and leave. You want Google and the other search engines to stay a while and really get an understanding of what each page is and means. To do this, your site content should be easy to read and should stay on topic. When writing up what each page will say, have your customers in mind and continually remind them of the product or service that you are offering them and why it fits their needs. Google will pick up on this topic trend and index your site for the keywords, and themes, you use.
Behind the actual text there is subtext which many of the search engines also will either display or use to rank search results. This is what we call metadata and typically isn’t seen when you visit a webpage. Each page on your website should be optimized with 3-5 keywords and a 2 sentence description in the metadata. This will also help sites find the relevant topic of the page so that when somebody types that word or phrase into a search engine, that page on your site (the relevant information) will appear in the results. 
Make sure to also choose a strong, descriptive URL because search engines will use text in your web address to find results as well. This, combined with you titles and header tags are two of the most critically important ways of getting your site indexed by the search engines in a way that will display the desired results to your users.
Finally, tag your media. If you are using an image, give it an appropriate name. Use tags for your videos and audio as well. Search engines have a hard time figuring out what the content of these things actually are so they are solely reliant on you tagging and naming your media appropriately in the metadata or caption areas.
Website load time and structure can also play a part in determining how well you are indexed and ranked. Make sure to keep your site simple for users and to avoid lots of fancy javascript and other code. Keep it simple, remember your audience and optimize each page for relevant keywords. Doing these things will put you on the path towards having more than just a website…but a destination.
