Illuminator-Pt.1 Ch.1 - Why the book has its title

"He dipped the pen into the ink and then faltered for just a second. A tremor had gone through his bowels. To mark the paper was the decisive act.In small clumsy letters he wrote: April 4th, 1984.
He sat back.
A sense of complete helplessness had descended upon him. To begin with, he did not know with any certainty that this was 1984. It must be round about that date, since he was fairly sure that his age was thirty-nine, and he believed that he had been born in 1944 or 1945; but it was never possible nowadays to pin down any date within a year or two. "

This passage shows a little bit behind the reason why this book has its title. 1984 was the year Winston thought it was, thinking, "It must be round about that date, since he was fairly sure that his age was thirty-nine, and he believed that he had been born in 1944 or 1945; but it was never possible nowadays to pin down any date within a year or two. " This was the year that Winston had written down for his first entry, the year Winston had first thought about rebelling against the Party, and it was the year he committed Thought Crime. The year is significant because throughout those years was when he first wrote in a diary illegally, had relations with Julia illegally, and attempted to join the Brother, which is obviously illegal, since the Brotherhood is an organization in itself a crime, because it's about rebelling against the party, which is considered a crime as well. This book is about the events that unfold in particular time Winston Smith's life, which happens to be 1984.