The truth is SEO (meaning Search Engine Optimization) is a lot of things all coming together to create a desired result. Trying to sum it all in one sentence--or even one paragraph--would give a picture that is fuzzy at best.
Your website should be your greatest ROI as far your business is concerned. Every aspect of your site should be geared towards making it your hardest working employee.
In this digital age where a business can realistically exist or market itself solely online and still thrive, one would be forgiven for thinking that print materials are no longer necessary--or at the very least can promise little ROI.