Nomination

Since 2004, Academy Award nomination results have been announced to the public in late January. Prior to 2004, nomination results were announced publicly in early February.

Voters
The Academy of Motion Picture Arts and Sciences (AMPAS), a professional honorary organization, maintains a voting membership of 5,835 as of 2007.
Actors constitute the largest voting bloc, numbering 1,311 members (22 percent) of the Academy's composition. Votes have been certified by the auditing firm PricewaterhouseCoopers (and its predecessor Price Waterhouse) for the past 73 annual awards ceremonies.
All AMPAS members must be invited to join by the Board of Governors, on behalf of Academy Branch Executive Committees. Membership eligibility may be achieved by a competitive nomination or a member may submit a name based on other significant contribution to the field of motion pictures.
New membership proposals are considered annually.The Academy does not publicly disclose its membership, although as recently as 2007 press releases have announced the names of those who have been invited to join. The 2007 release also stated that it has just under 6,000 voting members. While the membership had been growing, stricter policies have kept its size steady since then.

Rules
Today, according to Rules 2 and 3 of the official Academy Awards Rules, a film must open in the previous calendar year, from midnight at the start of January 1 to midnight at the end of December 31, in Los Angeles County, California, to qualify. Rule 2 states that a film must be "feature-length", defined as a minimum of 40 minutes, except for short subject awards and it must exist either on a 35 mm or 70 mm film print or in 24 frame/s or 48 frame/s progressive scan digital cinema format with native resolution not less than 1280x720.
The members of the various branches nominate those in their respective fields while all members may submit nominees for Best Picture. The winners are then determined by a second round of voting in which all members are then allowed to vote in most categories, including Best Picture.
As of the 79th Academy Awards, 847 members (past and present) of the Screen Actors Guild have been nominated for an Oscar (in all categories).