Why do people say today's chess is dominated by computers? Everytime I read articles on chess, I see people who say that chess nowadays is dominated by computers. For example if you look for a thread on the subject 'fischer vs carlsen' (just an example) you see people comment that if fischer had access to computers, he would have been better. Why? What do modern GM's do with computers?
Masters use computers as training tools.  They allow a master to quickly check the viability of variations and understand why some moves are good or bad.  Further, they afford searchable instant access to millions of positions and countless openings to the master.

In short, the computer is your sparring partner, second, and librarian, and who works for cheap.