Help! I don't know what it's called...

I'm fairly new to this and I want my blog page to look a certain way but I'm not sure what it's technically called when it looks this way.

Essentially, when viewing articles on a blog page I want them to show the title, image and the initial sentence or two with a "read more" link to take you to the full article. What is this called and how do I do it?

I've linked to an example of roughly how I would like articles to be displayed. ie. Title, featured photo and excerpt of text.

https://dl.dropbox.com/u/4831919/blog%20page.png

Thank you!