How to add, configure and remove widgets in WordPress
Widgets are used to add menus or some functions to the sidebars of your site or to any area on the frontend that allows widgets. The widget areas depend on the theme that you use. WordPress comes prepackaged with some widgets. They are all available to be added to any of the widget areas; some of them are active by default (they are added to a widget area), while others are not. By installing third party plugins you can expand the list of the available widgets with all sorts of widgets. You can find such plugins in the plugins section of the official WordPress site.
To add widgets to any of the widget areas or to delete widgets from a widget area, log in to the admin panel of your WordPress and go to Appearance menu>Widgets sub-menu. On the page that opens you'll see a list of the available widgets with a short description of each widget. On the right side are panels for the widget areas that are allowed on the frontend. To add an available widget to a widget area (e.g. a sidebar) and thus make it visible on the frontend, hover the mouse pointer over its name until it turns into a four-arrow cursor, then click and hold the left mouse button, and drag and drop the widget in one of the panels on the right corresponding to the area on the frontend in which you want the widget to appear.
Next to the name of each of the added/active widgets there's a small arrow. Clicking on it will expand a small panel with some settings. The settings that can be configured depend on the widget type. To remove the widget from the sidebar (or another area to which it's assigned), expand the panel with its settings and click on the Delete button in the lower left corner of the panel. If you have made some changes to its settings and you want to keep them in case at some point later you decide to add the widget with the same configuration, drag and drop the widget into the Inactive Widgets block on the left.
For screenshots and more details on widgets and the settings of all the default widgets that come prepackaged with WordPress check out our WordPress widgets tutorial.