Critical thinking is a combination of analysing and investigating skills we use when we are looking for rationality in a situation or statement, or when we decide wether or not a person is trustworthy

You could say that a critical thinker most importantly is awake and active while participating in or observing a situation, and he makes a judgement of this situation based on common sense, his former experiences from similar settings, and his own ideas of ration. He asks questions, consideres the options, and finds the answer. Within the term critical thinking we find a various of keywords, like skepticism, rationality, self-awareness, honisty, open-mindedness, discipline, and judgement.