What is it

What is open source?
Open source software is software whose code has been made publicly accessible and modifiable. Since this is the open source projects forum on Scratch, all open source projects here should be at least vaguely related to Scratch.

Source : https://scratch.mit.edu/discuss/topic/764435/

Open source projects is specifically for Scratch's github. People are meant to use this forum to discuss Scratch's actual bottom level programming here, though most people don't use it for this function.

Show and Tell is better when youve made a project you want other people to use, and advanced topics or developing scratch extensions are better for discussing modifications to Scratch or in general more obscure things.