Link: http://ellislab.com/expressionengine/user-guide/getting_started/index.html#turning-the-page
“At this point, you might notice that our site’s homepage (http://example.com) is showing the same content as our News page (http://example.com/news). The reason for this is simple: Every site has a default Template Group which gets shown as the homepage when no Template Group is specified in the URL. And since we’ve only created one Template Group, “news”, that’s automatically our site’s default, too.”
To confirm, this is in EE 2. In going through these steps (starting from scratch), I’ve actually had to go back in to edit the only template group that was there and set it as the default. This was NOT done automatically.
Recommend update to include this step here: http://ellislab.com/expressionengine/user-guide/getting_started/index.html#creating-a-template