What is a Widget?
WordPress widgets can add features to your website’s sidebars, footers, or other areas. Some default WordPress widgets are Categories, Tag cloud, Search, Navigation Menu, Calendar, and Recent Posts.
More About Widgets
In WordPress, you can add specific content or features to different template parts without writing a line of code. Depending on your current theme, you can add widgets to areas like the header, footer, sidebar, below blog post content, and more. Specific plugins can also expand the number of widgets you can use. For instance, a form plugin can let you feature a contact form in your sidebar or footer.
To add a new widget or customize your existing ones, go to Appearance > Widgets. Here you can choose from the list of supported widgets and drag them where you want them to appear on your site. This rearrangement will automatically update your theme.