There are a ton of ways to improve the SEO of your site pages. Search engines look for elements including title tags, keywords, image tags, internal link structure, and inbound links (also known as backlinks). Search engines also look at site structure and design, visitor behavior, and other external, off-site factors to determine how highly ranked your site should be in their SERPs.
With all of these factors taken into account, SEO primarily drives two things — rankings and visibility.