The main character, Winton, commits a bunch of crimes. He has a sexual relationship with Julia. He keeps a diary and writes "Down with Big Brother" in it. He seeks out an organization that supposedly exists to see the downfall of Big Brother. All of these are things are crimes against the ruling government; however, all of the crimes are thematically the same. Each crime is technically the same crime, because each crime is technically a thoughtcrime. Winston is doing all of his rebellious acts, because he hates Big Brother and the government system that is in place.
His punishment is capture and torture. The torture is a combination of both physical and psychological. That was a rough section to read, because I'm not a fan of rats either.
‘You understand the construction of this cage. The mask will fit over your head, leaving no exit. When I press this other lever, the door of the cage will slide up. These starving brutes will shoot out of it like bullets. Have you ever seen a rat leap through the air? They will leap on to your face and bore straight into it. Sometimes they attack the eyes first. Sometimes they burrow through the cheeks and devour the tongue.’
The result of Winton's torture was a complete brainwashing. Winston goes back to functioning as an automaton in complete support of Big Brother.
But it was all right, everything was all right, the struggle was finished. He had won the victory over himself. He loved Big Brother
Simply put, Winston commits thoughtcrime. More importantly, he knows he is committing thoughtcrime by a variety of actions such as writing in a diary, carrying on in an affair with Julia, seeking out the brotherhood and visiting the prole neighborhood. The sad part is, Winston cannot get away with this at all. The telescreens and thought police are too invasive, so it is only a matter of time before he and Julia are caught and imprisoned in the Ministry of Love, where they, ironically are tortured.
The punishment alternates between physical torture, where Winston is beaten, starved and given electric shocks, and emotional torture, where Winston is forced to endure his greatest fear, believe in the party's doctrines, and even betray Julia.