SEO's ultimate goal is to get new customers to patronize the business, whatever that looks like for that particular business. SEO 'could' be used for non-commercial content but that's not it's typical purpose. This is accomplished by getting people unfamiliar with the business to see their web pages and/or other appropriate online content as soon as possible after they type their money or research keywords in the search engines. SEO ranks the content as high as possible in the results pages using multiple on and off page SEO methods. SEO can be applied to text content, images, or videos. SEO must also be concerned with verifying that conversions take place from those web pages after people visit. There are several ways to monitor conversions: tools, using a forwarding phone number and/or email address that the SEO has control of, and/or having the business ask new customers upon contact how they found the business and documenting that information. As I have said multiple times in the past it doesn't help SEO at all to get people there if they don't feel comfortable contacting the business.