(Check sidebar for more information)

We defined a sidebar in class today as a short, separate piece of complementary text that places a larger story in context.

Sidebars are useful, and often essential, in delivering the full story to readers. They expand upon the information presented in the article, offer opposing viewpoints, or update the reader on late-breaking developments that didn't make it into the story. Sidebars are excellent tools for pointing readers to external sources of information. Some reporters even use sidebars to comment on their story-writing process or the challenges they faced while writing the story.

Their separation from the actual story helps the latter maintain focus. As always, brevity and conciseness are key to a well-written sidebar, as they are complementary, and not central, to the article.

Check these external links for more info on sidebars:

The Dabbling Mum's page on How to Write Sidebars.

About.com defines the sidebar.

(Sidebar one is from Cyberpat.com, Sidebar 2 is from Gregfelton.com)