The mom test a million times over! When people hear the name, they assume it's about usability (i.e. make something easy that your mom understands it), but it's

The mom test a million times over! When people hear the name, they assume it's about usability (i.e. make something easy that your mom understands it), but it's not - its' the best book on customer development that exists. I recommend it to every startup person I meet.