There are situations where you might want to put the same block on several pages. For example: If your page has a picture in the head of each page, it would be helpful if there's a default picture block in each page you create. For a small page, the navigation is probably identical on each page.

In concrete5 you can manage not only the page content, but also the page type content. What does this mean? Since every page is derived from a page type, they behave like templates. Blocks in the page types are, by default, placed in every new page. It's also possible to add blocks to existing pages by modifying the page type defaults on each page as well.