Online chess is more popular than ever. However, it is fairly easy to cheat. For example, my phone plays better chess than most, if not all, professionals. For this reason, chess servers crack down on this kind of behavior with sophisticated cheat detection methods, and chess.com is probably the best at this.
I played a chess.com USCF Online Rated tournament Friday night where I was doing pretty well until the final round where I lost to a lower rated player. As a result, I got 4th place. However, chess.com has analysis tools that show how well a player played. My opponent who beat me played 99.6% accurate against me, which is unlikely that anything less than a computer could achieve this result. His other games showed similar accuracy, so I reported my opponent to chess.com and they agreed that he was cheating. They not only deleted his account, but it is my understanding that my loss will be reversed which will put me in first place.
This is about the 5th time that this has happened to me. Cheating seems to be rampant, despite the servers attempts to crack down on it.