Widgets are an easy way to add different types of content to the side columns of your site. Although there are basic widgets available to you, be sure to check out the Widgets and Plugin categories to find other pieces of information you can add to your site.
Assigning tags to your posts is an excellent practice and just another way for visitors to find information. However, to ensure users have access to those tags, you’ll need to make them available on your site by enabling the Tag widget.
RSS (Really Simple Syndication) is a way web sites make their content available away from their site (watch this video for an explanation of RSS). Using RSS feeds, you can post news and information from other sites into your sidebar automatically!
One of the great features of WordPress is the ability for visitors to leave comments about what you write and often visitors want to see what others have said. The Comments widget automatically posts recent comments in your sidebar.