Spreadsheets and text documents are by nature very powerful and well-designed interfaces; they are the result of many years of expertise from Google and other previous designs as well, but for some use cases there are just too many possibilities.

If you have already found one of your cherished and carefully prepared documents completely messed up by someone after you gave them access to it, you'll understand what I mean.

It is not always a question of malice or wickedness but, very often, a simple matter of incompetence.

Building a user interface with restricted possibilities solves that problem radically; it just requires a little more work from our side and that's what we're going to try now.

This chapter is about standalone web apps and UIs; we'll see that there are also many situations in which we don't need a user interface and others in which applications respond to parameters or even work entirely on their own without any user interaction.