Take a look at a picture of a mechanical typewriter: http://blog.gngcreative.com/wp-content/uploads/2015/02/mi0fg2Q.jpg http://blog.gngcreative.com/wp-content/

Take a look at a picture of a mechanical typewriter: http://blog.gngcreative.com/wp-content/uploads/2015/02/mi0fg2Q.jpg http://blog.gngcreative.com/wp-content/uploads/2015/02/mi0fg... Those metal things you can see there, those are tabstops. They are called tabstops because when you press the tab key, the carriage mechanically stops at the tabstop. Tabstops were placed every 8 characters. A tabstop is simply a way to "type" 8 spaces with one keypress. Github is not the only page that uses 8 spaces for a tab, and it's definitely not inexplicable. The Unix/Linux terminal uses 8 spaces by default if you insert a tab. Vim uses 8 spaces by default if you insert a tab. Python considers a tab to be equivalent to 8 spaces. I'm sure there are a lot of other systems that default to this value. If you want to control how an indentation looks, use spaces. If you want tabs because the size is configurable and can be adjusted to one's preferences, you can't at the same time complain about "unreasonable configurations" that others use :)