When you build a website, there's always some content which is identical on several pages. For instance: A logo, an address, or a phone number if it appears on several pages. It's rather annoying if you manually have to make sure all the pages are updated, it takes quite some time and if you fail you'll quite likely get some complaints.

If you want to make things quick and dirty, put them in your PHP/HTML code and you're done. But you don't want to make things dirty, and luckily you don't have to because there's a scrapbook which is going to help you to get out of this misery.