The prototype docs have moved to a new website with an improved format. This documentation page can now be found here: https://lua-api.factorio.com/latest/types/string.html
This wiki page is no longer updated and will be removed at some point in the future, so please update your browser bookmarks or other links that sent you here. If you'd like to contribute to the new docs, you can leave your feedback on the forums.
Strings are enclosed in double-quotes, like this "hi".