Too Long; Didn't Read
Broadly speaking, usability testing is a technique used in usercentered interaction design in order to evaluate a product by testing on users. It allows companies to test a basic version of mobile app or website before dedicating time toward coding and developing stage. Why worry about usability so early when prototyping already has a big todo list? Because “<em>Unless your product is usable, all your testing will tell you is that people don’t like terrible products</em>”.