Push and Pull classes
See this post for details.
My tale
It was the best of times, it was the woof of times.
Resize the browser to see the page reform with the image above the text.
The "pull" class was applied to this text column while the "push" class was applied to the image column.
The "row" class
There are no push or pull classes applied. When the browser size gets smaller the columns will reform top to bottom.
1. Sed maximus enim felis, et interdum risus vehicula vel. Mauris vitae ligula vulputate, facilisis odio eget, accumsan lacus. Pellentesque suscipit ante leo, sed consectetur magna aliquet at. Fusce consectetur ullamcorper rhoncus. Fusce ac aliquam nisl. Vestibulum ac congue lorem.
2. Sed maximus enim felis, et interdum risus vehicula vel. Mauris vitae ligula vulputate, facilisis odio eget, accumsan lacus. Pellentesque suscipit ante leo, sed consectetur magna aliquet at. Fusce consectetur ullamcorper rhoncus. Fusce ac aliquam nisl. Vestibulum ac congue lorem.
3. The "row class has been applied to this div. Sed maximus enim felis, et interdum risus vehicula vel. Mauris vitae ligula vulputate, facilisis odio eget, accumsan lacus. Pellentesque suscipit ante leo, sed consectetur magna aliquet at. Fusce consectetur ullamcorper rhoncus. Fusce ac aliquam nisl. Vestibulum ac congue lorem.
4. Sed maximus enim felis, et interdum risus vehicula vel. Mauris vitae ligula vulputate, facilisis odio eget, accumsan lacus. Pellentesque suscipit ante leo, sed consectetur magna aliquet at. Fusce consectetur ullamcorper rhoncus. Fusce ac aliquam nisl. Vestibulum ac congue lorem.