If you are interested in knowing how a website you visit (or a website you manage) is ranked by Google you can use the the Open SEO Stats (formerly PageRank Status) extension for Google Chrome. You can also use the PageRank add-on for Firefox. These tools allow you to see the PageRank of the page you are visiting in the toolbar of the browser. They also give the Alexa rating of the website – with the Chrome extension giving more detailed information.
The PageRank is one of the systems that Google uses to weigh the popularity and relevance of websites. The higher your PageRank, the more likely you are to appear at the top of Google search results. Smaller websites may find it more difficult to increase PageRank but a low rating does not necessarily mean poor content. It may just be an indication that better search engine optimization is necessary.