Widgets are one of the native mechanisms in WordPress. Their main purpose is to provide us with an easy-to-use way of customizing the sidebars, footers, and headers of our sites, with the addition of extra content. Even though the most common placement of widgets is indeed the sidebar, the only actual rule is that a widget must be displayed inside a widget area, and a widget area can be anywhere a theme developer wants it to be. Common widgets contain the following:
- A monthly archive of blog posts
- A clickable list of pages
- A clickable list of recent posts
- A metadata box (containing logon/logutout links, RSS feed links, and other WordPress links)
- Recent comments posted on the blog
- A clickable list of categories
- A tag cloud
- A block ...
