Show Structure: Episodic vs. Arc

There are two basic structures of television (and this is being very broad): the episodic structure and the arc structure. Historically, sitcoms tend to be more episodic, and hour-long dramas are more likely to fall under the "arc" umbrella. This is shaken up every once in a while: Law and Order is distinctly episodic, while How I Met Your Mother definitely has an arc structure.

Television structure definitely falls on a spectrum from episodic to arc, with shows exhibiting each to varying degrees. On the furthest end of episodic, you have shows that have more of a recurring theme than anything else—including cast. The Outer Limits and The Twilight Zone fall under this heading.

Episodic shows can be described as shows in which the episodes are, for the most part, self-contained. You don’t have to watch every episode, or watch it entirely in order, for the show to make sense or be enjoyable. You can miss an episode here or there, and you won’t be completely lost. You probably shouldn’t mix up episodes from different seasons, and I’m not saying episodic shows can’t have storylines that extend beyond a single episode. Most of the time, though, if you forget to watch or switch a few episodes around, it won’t make a huge difference.

Probably the farthest on the arc end of the spectrum is the season/series-long plot arc. This is often a mystery, exemplified in shows like Twin Peaks and Veronica Mars. The mystery is one of the easier plot arcs to manage, because you can have a contained plot within each episode while still inching forward on the overarching plot with clues and new discoveries.

Somewhere in the middle is the character arc. The showrunners may know where the character or characters are going throughout the season, but if you miss an episode or two, you’re probably not going to be super-confused. A lot of episodic shows will still have a character arc, but it’s less overt than “Oh look, another clue!” and therefore the episodes are more self-contained.

Shows that are arc-heavy are high-risk, high-reward for networks. Chances are, if the viewer gets invested, they’re likely to continue watching with frequency. All other things being equal (like, for example, quality), arc shows tend to be good at retaining audience. On the other hand, the more complex the plot arc, the less likely the show is to gain viewers. It’s a balancing act, and arc-heavy shows that don’t hit the ground running are often quickly canceled. Viewers have begun to take this to heart, and many won’t start watching an arc show until it appears like it will be around for a while. Shows with ongoing plot arcs often hurt the most when they’re canceled, because there are so many dangling plot threads. Arc shows are dangerous for networks and viewers, but when they work out (like Lost), they work out amazingly well.*

*Until 50% of your audience is dissatisfied with your ending. But no one's perfect.