The most common example of a widget area is a sidebar located next to the content on a site. They’re also frequently included in site footers. Every WordPress installation includes default widgets like “Categories”, “Text”, “Recent Posts” and “Recent Comments”. More widgets can be added by themes and plugins active on the site, and they can also selectively remove the default WordPress widgets if they are replaced by a widget in the theme or plugin (a custom “Recent Posts” widget displaying a featured image for each post, for example).
Widgets are edited in Appearance → Widgets in the administration panel, but the “Widgets” link is only displayed in the Appearance menu if the active theme supports widget areas. You can also edit widgets from within the customizer. You add a widget by dragging it from “Available Widgets” to one of the widget areas. Widgets usually include a number of different settings that determine what content to display and how to display it.