The production of The Simpsons is a complex work of supervision, writing, recording and animation, which needs lots of people to complete, as any other TV show. As technology progresses, so does production, with the inclusion of "digital ink and paint" and HDTV.
Creating an episode of The Simpsons consists of writing, then voice acting and finally animation. However, episodes take a lot of time to make, approximately 5 months, so several episodes need to be produced at the same time.
Writing of episodes takes place in a room with sixteen writers who pitch ideas for episodes. The show runners chose a general plot of each of the episodes and a writer is assigned for an specific episode. The main writer of each episode writes the first draft. Group rewriting sessions develop final scripts by adding or removing jokes, inserting scenes, and calling for re-readings of lines by the show's vocal performers.
Once the script is done, it is time for the voice actors to record their lines. The voice acting usually takes 1 or 2 weeks per season. The show has six main voice actors: Dan Castellaneta, Julie Kavner, Nancy Cartwright, Yeardley Smith, Hank Azaria and Harry Shearer, with several other supporting cast and frequent guest stars. They read the script and perform the voices to a microphone in a studio.
While the voice acting is taking place, the animation is being done. For the first three seasons, the animation company was Klasky Csupo and other studios subcontracted by FOX, which are AKOM, Anivision, Rough Draft Studios, U.S. Animation, Inc., and Toonzone Entertainment. Klasky Csupo made the animation in the United States and the rest made the animation at Korea. However, starting season 4, Gracie Films switched the main animation company to Film Roman, Inc.
Artists at the U.S. animation studio, Film Roman, draw storyboards, design new characters, backgrounds, props and draw character and background layouts, which in turn become animatics to be screened for the writers at Gracie Films for any changes to be made before the work is shipped overseas. The Korea studios then do the rest of the animation, which is more detailed, like the in-between movements (the drawings needed between the main drawings made at Film Roman to complete the movements) and the painting. This is all supervised by the directors and animation directors. Then the finalized animation is delivered back to United States and then to FOX.
Since season 1 to season 14, episodes used traditional cel animation, which was made by drawing the characters in the cel papers and painting them manually. However, since season 14, the show uses digital ink-and-paint, which is done by digitalizing the cel papers and coloring them digitally.
Sometimes, when faster animation fits better (such as planes, flying or rolling elements), 3D animation is used.
Since season 20, the show is broadcast in high-definition, which allows for better detailed images.