"Widgets?" you ask, "Whosits, whatsits, whatchamacallits, and dingdongs?"
Web Widgets are incredibly popular and you've probably seen a thousand if you've seen any at all. They live in the sidebars, headers, and footers of websites and they tell us the weather, update us with the latest news, display slide shows and videos, enable us to play mini games and display our social networking updates from Facebook, Twitter and so on. Widgets are a way to enhance your website with any of the myriads of applications available across the web for embedding on your site.
Read more about widgets on the web here, http://en.wikipedia.org/wiki/Web_widget