offpage SEO is all the SEO that is not handled by directly affecting or manipulating code or content directly on your site.
Hi Off page SEO is the techniques in which we do not make any changes in site and able to rank our website with our targeted keywords.
off page means the list of different type of activities which are not doing on website but it is the activities of promote the information like keywords, page url, description etc in other websites by different types of off page activities.
Nice insights, and good question by the OP. Just one point to note, how you initially set up your site determines a lot how your site will perform in offpage SEO. There are things that should be done right the first time. Keep it here to learn more on this. But just a hint, they include crawling, indexing, among others.
off-page SEO is what can be done off the pages of a website to maximize its performance in the search engines for target keywords related to the on-page content and keywords in off-page direct-links.