Components are larger extensions that produce the major content for your site. Each component has one or more "views" that control how content is displayed.In the Joomla! administrator there are additional extensions suce as Menus, Redirection, and the extension managers.
The content component (com_content) is what you use to write articles. It is extremely flexible and has the largest number of built in views. Articles can be created an edited from the front end, making content the easiest component to use to create your site content. Help
The search component proviedes basic search functionality for the information contained in your core components. Many third part extensions also can be searched by the search component. Help
News Feeds (com_newsfeeds) provides a way to organize and present news feeds. News feeds are a way that you present information from another site on your site. For example, the joomla.org website has numerous feeds that you an incorporate on your site. You an use menus to present a single feed, a list of feeds in a category, or or a list of all feed categories. Help
The users extension lets your site visitors register, login and logout, change their passwords and other information, and recover lost passwords. In the administrator it allows you to create, block and manage users and create user groups and access levels. Help
Please note that some of the user views will not display if you are not logged in to the site.
Weblinks (com_weblinks) is a component that provides a structured way to organize external links and present them in a visually attractive, consistent and informative way. Help