Season 0 of The Office premiered on July 13, 2006.

Season 1 of The Office premiered on March 24, 2005.

This season introduced the main characters, and established the general plot, which revolves around Michael Scott, regional manager of the Scranton branch office, trying to convince the filmmakers of the documentary that he presides over a happy, well-running office. Meanwhile, sales rep Jim Halpert finds methods to undermine his cube-mate, Dwight Schrute; receptionist Pam Beesly tries to deal with Michael's insensitivities and flubs; and temporary employee Ryan Howard is acting mostly as an observer of the insanity around him.

Season 2 of The Office premiered on September 20, 2005.

Beginning with "The Dundies", the second season further developed into the plot of the fear of company downsizing, along with the introduction of new characters and developing some of the minor ones—especially that of Dwight Schrute. Michael Scott soon starts a relationship with his boss Jan Levenson and, Pam Beesley and Jim Halpert’s relationship become one of the focal points of the season. Their compatibility becomes more obvious as Jim’s feelings for Pam continue to grow, while she struggles with her relationship with the warehouse worker Roy Anderson.

Season 3 of The Office premiered on September 21, 2006.

The season marked the move of main character Jim Halpert from Scranton to Stamford, and also introduced Rashida Jones as Karen Filippelli, and Ed Helms as Andy Bernard—both members of Dunder Mifflin Stamford—as recurring characters. The main plot for the early episodes of the season deals with a recurring problem in seasons one and two—the problem of company downsizing—while in the last half of the season, inter-office relationships also became a major plot point.

Season 4 of The Office premiered on September 27, 2007.

Season four marked the departure of Karen Filippelli as a regular character, although she appeared for a few seconds in the first episode, "Fun Run" and in the sixth episode, "Branch Wars", as the regional manager of the Utica branch. Relationships again emerged as the main theme of the season, with Jim Halpert and Pam Beesley's rising, and Michael Scott and Jan Levinson's, as well as Dwight Schrute and Angela Martin's declining. Technology was another prevalent theme as the office staff struggled with initiatives introduced by Ryan Howard to modernize the company.

Season 5 of The Office premiered on September 24, 2008.

Michael Scott and his fellow Dunder Mifflin-ites steal customers, frame co-workers, and indulge in intra-office love affairs.

Season 6 of The Office premiered on September 16, 2009.

In Season 6, the crew faces romances, marriage, parenthood, new corporate ownership, Darryl’s rise to middle management, and a ball-busting new boss.

Season 7 of The Office premiered on September 22, 2010.

In Season 7, Dwight is now the owner of the building, Andy is courting Erin, Jim and Pam struggle with being new parents, and past girlfriends haunt Michael.

Season 8 of The Office premiered on September 22, 2011.

The eighth season largely centers around Andy Bernard's ascension to regional manager, as well as the antics of Robert California, the new CEO of Sabre, a fictional printer company that owns Dunder Mifflin. Halfway through the season, Dwight Schrute —along with Jim Halpert, Stanley Hudson, Ryan Howard, Erin Hannon, and Cathy —travel to Florida to help set up a Sabre Store, where Nellie Bertram is introduced.

Season 9 of The Office premiered on September 19, 2012.

In Season 9, Andy finds his true calling in showbiz, Jim lands the job of his dreams, Erin struggles with love, and Angela's marriage isn’t what it seems.