What do critics do?
Critics criticize things. When you criticize something, you
point out flaws, explain what you think of it, say how it could be
improved, etc. Everybody criticizes everything to some extent, but
there are some professional critics who get paid to do their job.
Whenever you see the reviews of a restaurant, these are written by
critics. When you see the "New York Times raves- fantastic!" in
movie trailers, these things were said by critics.