What is a state in React and how is it used?
States are at the heart of components. They are the source of data and must be kept simple. States determine components’ rendering and behavior. They are mutable and create dynamic and interactive components, and can be accessed via this.state().
Note: From the vast number of react developer interview questions, answering this will help you to align yourself as an expert in the subject. This is a very tricky question that often makes developers nervous.