Substance is a new platform for the online authoring of texts. You can use it to write down pretty much anything. If you’re attending College, you can use it to write essays and papers, and if you aim to become a professional writer then you can work on stories and scripts with any creative partner you might have. The site can be used for free in all cases, with you being able to type your text and making as many changes as you want thanks to the practical interface that is provided. This interface emphasizes semantics over rigid structures, and (as such) only the most essential formatting options are provided.

As it stands right now, others can’t directly edit what you’ve written. Rather, they can comment on it, and you’re going to make the necessary changes based on what they tell you. But a future version of the service is adding larger collaboration capabilities, and letting other submit patches that you (as the owner of the document) can have instantly applied.