Google used to publicly display the PageRank of webpages in its toolbar, but since black hat SEOs use that information to help their rankings, Google now keeps the PageRank score private.
Essentially, every time a page links to another page, it passes on a portion of its PageRank (or link equity). This means that pages with a lot of backlinks will pass more PageRank than other pages.
Unlike Domain Authority, PageRank is actually a ranking factor that Google relies on when promoting web pages. So, while Google no longer lets us know PageRank directly, website owners need to be aware that each hyperlink still delivers PageRank (or link juice) throughout the Internet.