What is (a) substack?

[KarenB]

I have recently noticed a few people
I follow on Instagram add a link to their substack page. I think it may be a space for writers to share their content, but not sure. If so, I know I would enjoy it. My social media is limited to Facebook, which is boring to me anymore, and a private Instagram page. Coud someone explain this to me?

 

[disneychrista]

https://substack.com/#:~:text=A Sub...ers’ inboxes—in email and in the Substack app.

 

[Karin1984]