Academy Awards of Merit were presented in 24 standard competitive categories at the February 26, 2012, ceremony. Nominations for these awards were announced by AMPAS on January 24, 2012. In addition, three Honorary Academy Awards were presented at the 3rd Annual Governors Awards ceremony held on on November 12, 2011.
The 84th annual Academy Awards ceremony was hosted by Billy Crystal and produced by Brian Grazer. The ceremony marked Crystal’s ninth time serving as host for the Academy Awards. The ceremony was originally scheduled to be hosted by Eddie Murphy. However, Murphy stepped down after Brett Ratner resigned as producer, following Ratner's use of a gay slur when discussing rehearsals.
The Artist and Hugo each won five awards, with the former winning Best Picture and its star Jean Dujardin winning Best Actor. The Iron Lady won two awards, including Best Actress for Meryl Streep. The Artist became the first silent motion picture in 83 years to win Best Picture (after Wings, which won Best Picture in the 1st Academy Awards).
Check out the list below for the winners in the order they were announced at Sunday night's Academy Awards show.
Best Cinematography: Robert Richardson, "Hugo"
Best Art Direction: Dante Ferretti and Francesca Lo Schavo, "Hugo"
Best Costume Design: Mark Bridges, "The Artist"
Best Makeup: Mark Coulier and J. Roy Helland, "The Iron Lady"
Best Foreign Language Film: "A Separation"
Best Supporting Actress: Octavia Spencer, "The Help"
Best Editing: Kirk Baxter and Angus Wall, "The Girl With the Dragon Tattoo"
Best Sound Editing: Phillip Stockton and Eugene Gearty, "Hugo"
Best Sound Mixing: Tom Fleischman and John Midgley, "Hugo"
Best Documentary: "Undefeated"
Best Animated Feature: "Rango"
Best Visual Effects: "Hugo"
Best Supporting Actor: Christopher Plummer, "Beginners"
Best Original Score: Ludovic Bource, "The Artist"
Best Original Song: Bret McKenzie, "Man or Muppet"
Best Adapted Screenplay: Alexander Payne, Nat Faxon and Jim Rash, "The Descendants"
Best Original Screenplay: Woody Allen, "Midnight in Paris"
Best Live Action Short: "The Shore"
Best Documentary Short: "Saving Face"
Best Animated Short: "The Fantastic Flying Books Of Mr. Morris Lessmore"
Best Director: Michel Hazanavicius, "The Artist"
Best Actor: Jean Dujardin, "The Artist"
Best Actress: Meryl Streep, "The Iron Lady"
Best Picture: "The Artist".
Source: http://www.huffingtonpost.com/2012/02/27/oscar-winners-list-2012-academy-awards_n_1303169.html and http://en.wikipedia.org/wiki/84th_Academy_Awards#Nominees_and_winners