From the article:
Billboards placed along interstates display large, simple messages to attract the attention of drivers. With cars whizzing by, billboard designs must be eye catching and succinct to have any chance at persuading passersby to pull off for a burger or to visit a local attraction. Many web users are like drivers, flying through websites with their heads glancing left and right. A user passing by your site may only stop for 3-5 seconds before cruising right along. Using large, bold typography will ensure that users understand your message loud and clear.
Here are several tips to make sure your message gets across in BIG BOLD LETTERS.