Pregunta de entrevista de Smartling

What is a general expression? What is HTTP? Whats the difference between state and props in React? Why make state immutable and give me an example of when you did. Difference between map(), filter(), and reduce()? What is "this" in Javascript? What is recursion and give me an example of an application of recursion. What is the purpose of the React "key" keyword ? What is box sizing and border box?