In 1984, the four Ministries are the Ministry of Truth, the Ministry of Love, the Ministry of Peace, and the Ministry of Plenty. It's notable that early on in 1984's first chapter, Smith refers to the four Ministries in terms of euphemisms:

The Ministry of Truth, which concerned itself with news, entertainment, education, and the fine arts; the Ministry of Peace, which concerned itself with war; the Ministry of Love, which maintained law and order, and the Ministry of Plenty, which was responsible for economic affairs. Their names, in Newspeak: Minitrue, Minipax, Miniluv, and Miniplenty.

In reality, the Ministry of Truth is responsible for the control and manipulation of information, the Ministry of Love with political suppression and torture, the Ministry of Plenty with rationing, and the Ministry of Peace with war.

As has already been said, each of these names involves a contradiction, and this contradiction is actually very much by design. The titles of the four ministries are cited within Book Two, Chapter Nine as examples of doublethink. This reflects the degree to which the State actively manipulates the perception of reality, in order to advance its own designs, and maintain its hold on power.

1. Miniluv: Ministry of Love (law and order)
2. Minipax: Ministry of Peace (war)
3. Miniplenty: Ministry of Plenty (rationing)
4. Minitrue: Ministry of Truth (propaganda)

Each of the ministries does just the opposite of what it says, like the Ministry of Defense in the U.S. (it's really the Ministry of War).

The Ministry of Love tortures political prisoners.

The Ministry of Peace wages war.

The Ministry of Plenty controls and rations the food supply to keep people near starvation.

The Ministry of Truth (where Winston works) spreads lies (propaganda), and it censors all print media, revises history, and truncates the language with each edition of the Newspeak dictionary.