Canvas mode is used for changing the design of a page or editing content. Once you're in Canvas Mode, you are editing an unpublished version of the web page - no changes you make are immediately live.
You can scroll through different versions of a page by selecting them from the dropdown in the bottom corner. This allows you to save different drafts a page, as well as toggling back to what the live view looks like.
If you make some changes that you didn't mean to do, you can always click that dropdown and go back to 'Live Page' to go back to the start with how the page looks on the live website.
Canvas mode is perfect for trying new fonts, different colours and adding new content blocks. If you have any trouble using it, you can always contact us for support.