[1] A web widget commonly provides users of the host page access to resources from another web site, content that the host page may be prevented from accessing itself by the browser's same-origin policy or the content provider's CORS policy.
That content includes advertising (Google's AdSense), sponsored external links (Taboola),[2] user comments (Disqus),[3] social media buttons (Twitter,[4] Facebook), news (USA Today),[5] and weather (AccuWeather).
[6] Some web widgets though serve as user-selectable customizations of the host page itself (Elfsight, Powr, OpenWidget).
Widgets may be considered as downloadable applications which look and act like traditional apps but are implemented using web technologies including JavaScript, HTML and CSS.
The use of widgets has proven increasingly popular, where users of social media are able to add stand-alone applications to blogs, profiles and community pages.
One example is the Facebook "Secret Crush" widget, reported in early 2008 by Fortinet as luring users to install Zango adware.
Because the host can always take the Widget down, it assures a large degree of mutual advantage and satisfaction with performance and content.