On-page SEO refers to everything you do directly on your website to improve its search rankings. Off-page SEO refers to everything you do outside your website to build its reputation. Both feed the same goal, more qualified organic (unpaid) traffic, but they work in very different ways.
What on-page SEO covers
On-page SEO makes your content better for both users and search engines. In practice, that means writing unique, descriptive titles for every page, linking your pages together so visitors, and Google, can find related content easily, and optimizing images so they load fast and carry the right context through alt text.
What off-page SEO covers
Off-page SEO is mainly about reputation. That includes earning links from other credible websites, staying active on social media, and managing how your business is reviewed on external platforms like your Google Business Profile.
Why you need both
Google weighs both on-page and off-page signals when ranking a page, so balancing the two is what actually moves you up the results. A technically perfect page with zero external credibility will struggle just as much as a well-linked page that's poorly optimized on-site.
Where to start
Generally, start with on-page SEO. It's foundational, it helps Google understand your pages and ensures visitors have a good experience once they land, and unlike off-page work, you're in full control of it since it only involves changes to your own site. Off-page SEO takes longer because you're relying on others, other sites, reviewers, platforms, to vouch for you. But all else being equal, Google will rank the site with the stronger reputation over the one without it, which is exactly why off-page work matters for holding a competitive edge long-term.