Ghost Theme Tips: Defining Content Blocks

In recent weeks I've seen a question popping up regularly:

If I've got some area in my default.hbs file, but I want it to contain information that changes depending on the post or page I'm viewing (for example meta data), can I do that and if so how?


This is a companion discussion topic for the original entry at https://dev.ghost.org/ghost-theme-tips-defining-content-blocks/