Segmented episodes

A three-parter is a Futurama episode that includes three different stories, often framed in and often non-canon.

The first three-parter was "Anthology of Interest I" in the second season, though the writers already added the Roman numeral to mark an interest in making more, like "Anthology of Interest II" from the third season. The Anthology of Interest episodes feature an invention of the Professor, the What-If Machine. When asked a what-if scenario (for example what if Bender were Human), the What-if Machine simulates the scenario on screen, and it is shown to the Planet Express crew and the viewers of the episode. These episodes thus feature a canon frame, surrounding three what-if scenario stories.

The first three-parter episode not being a part of the Anthology of Interest series was "The Futurama Holiday Spectacular" from the sixth season, which featured three different non-canon holiday stories. The upcoming "Reincarnation" will also be a three-parter and presumably non-canon, featuring the Futurama series in three different animation styles.