This page is a staging ground for notes that will eventually be moved into more permanent places.
The pager assumes you have a lot of data that you want to display, and that you want to break the list down into smaller chunks to be displayed one at a time. The most common use case is probably displaying search results, but you may wish to chunk up any long list of things: courses offered at a school, files in a database, a list of email messages...
The Pager offers the controls to the user to select which chunk of the whole list to view.
If you've ever used the Google search engine, you've seen something like the Pager - the "Goooogle" shown at the bottom of each page of results, with page numbers and 'Next' and 'Previous' - that's the functionality that the Pager offers.
The Pager currently doesn't figure out how many items there are in total, nor how many pages there are. That's up to you to figure out.
The current version of the Pager is entirely mark-up driven. This means that the Pager component itself doesn't create or provide any markup - you have to provide it yourself.