Pagination is a technique for limiting output. Think of Google search results, shopping the electronics category on Amazon, or browsing tagged questions on Stack Overflow. Nobody could consume all of the results in a single shot, and no site wants to spend the resources required to present them all to us, so we are offered a manageable set of results (a “page”) at a time.
In the most basic cases, we can implement this functionality in SQL Server by using OFFSET/FETCH. The problem is that anything that uses TOP or OFFSET will potentially have to scan everything in the index