A Substack newsletter can be many things. But it's almost always a serial publication – at least in a broad sense of the word "serial,” and sometimes a more specific sense.
What can go into a Substack newsletter?
A Substack newsletter can include:
text (including footnotes)
images (plus alt text and captions)
animated GIFs
videos
audio
podcasts
tweets
One newsletter can be almost all text. Another can be podcasts. A third can be a mix of several media.
The subject matter can be anything, as long as it doesn't violate Substack's terms of use. Among other distinctions, it could be nonfiction or fiction.
No matter what the content, a newsletter is a serial publication: it’s a series of posts.
A newsletter is always a serial, in a broad sense of that word. (The exception would be a newsletter that has only one issue and is never published again.)
Dictionaries, such as Merriam Webster, have several definitions of “serial" as an adjective or noun. Other than in particular areas (music, computers, finance, crime), the definitions apply in significant part to newsletters.
The most general meanings in Merriam-Webster don't fit perfectly – but they’re close enough in my opinion:
“of, relating to, consisting of, or arranged in a series, rank, or row”
“a publication (such as a newspaper or journal) issued as one of a consecutively numbered and indefinitely continued series”
In other words, a series of posts – which may have something in common, such as subject matter, but not necessarily – essentially makes a newsletter a serial publication. I don't think precise numbering or arrangement is important. As long as it's a series, it's a serial.
If that doesn't convince you, the definition of "serial” in the Online Dictionary for Library and Information Science should suffice:
A publication in any medium issued under the same title in a succession of discrete parts, usually numbered (or dated) and appearing at regular or irregular intervals with no predetermined conclusion.
Each post in a serial is part of something bigger.
Is the definition significant? I think so. A newsletter creator can see each post as adding to what was published before and leading to future publication. The first, or even the 100th, post is part of a greater journey.
The “serial” mindset can help the creator to view the newsletter as some (many? most?) subscribers see it: the newsletter is about something. Even if the newsletter is about “randomness,” or “nothing, like on Seinfeld,” or “whatever the author feels like saying that day,” it's still about something!
In the specific sense of presenting parts of one story, some newsletters are serial publications.
Now we get to the part about Charles Dickens and Sarah Koenig. A serial is also defined by Merriam-Webster as:
“appearing in successive parts or numbers”
“a work appearing (as in a magazine or on television) in parts at intervals”
Charles Dickens rose to fame with the serial novel The Pickwick Papers, published in monthly installments. He proceeded to publish other works as serials, as did many other writers.
The serial format has adapted over time to other media such as radio and television. It has returned to prominence in podcasts such as Serial. Co-created and presented by Sarah Koenig, each series of Serial is devoted to one story relating to crime or criminal justice.
(Incidentally, Koenig and Dickens both had an interest in exposing injustice through their serial productions.)
On Substack, a creator might state outright that the newsletter is or includes a serial. Or the creator might label each post as a “Chapter,” “Part,” or something similar. One way or another, the creator indicates that the posts are parts of one work. (When the work is completed – or even still in progress – the creator might start a second work. The creator might also publish other posts that aren’t part of the serial.)
Here are a variety of Substack newsletters that are or contain serials in a specific sense.
1,000 Ways to Die in Wyoming: “A serialized novel by FVGrego”
At Sea: “A serial about a group of friends on a trip”
Breakfast Serials: “serial stories you can eat breakfast to”
Bryan Ray: “Public Private Diary”
Classic Ghost Stories Podcast: “Classic Ghost and Horror Stories Read Out Every Week”
Connectom: “A newsletter at the intersection of science, technology and philosophy. A periodical for the mindfully adventurous. A creative resource for the life-long learner. A search to encounter new ways of thinking.”
The Constance Project: “A network of true stories, connected by one fascinating life”
The Examined Life: “Join me in this monthly (bi-monthly for paid subscribers) examination of the waking life. Let's make meaning together. Come along.”
I'd Rather Be Thin Than Famous: “Music Music Music Culture Culture Culture Ramblings”
Inhaling aspirations, again!: “Back to basics.”
An Intergalactic Relationship: “Part of The Galaxy Girls Series by Gregory L. Lane”
Jack Stack: Posts and writing from Jack Allison. Currently releasing a sci-fi novel called The Canopy On Moon as individual chapters, and other stuff.”
Jeff Einstein 2.0: “Social criticism essays and my exciting new serial novel, ‘The Golem and the Messiah’ -- about what really happens when the technomedia elite take over in the very near future...”
Letters from Annie: “I peaked in kindergarten”
Leverage: “The untold true story of the fight for student debt cancellation and free public college from Occupy Wall Street to the Debt Collective - By Ann Larson”
Life in a Vineyard: “A year’s journal living in a vineyard in Napa, Calif.”
Lifts and Lies: “A fictionalized look at what really goes on behind the scenes in the boutique fitness industry”
Lupus Yonderboy: “Chaos, Mr. Who. That is our mode and modus. That is our central kick.”
mary’s Newsletter: “A trial run at serial fiction”
Mia Moss' Breakfast Serial: “Harper Luna's account of the settlement and exploration of Outpost 3 on the planet Ocasta, along with her favorite recipes and cooking tips.”
Moose Nuggets: “A journey through one dog's testicles”
The Nick Warner Chronicles: “Adventures for All Ages”
Novella: “A novella in eight parts, inspired by the canvases of Léon Spilliaert
The Oregon Way: “Conversations exploring common priorities across Oregon”
The Queen City Historical Review: “Historical and nostalgic dispatches from Cincinnati, Ohio and Northern Kentucky.”
Regrounding the Landscape: “An Anti-Racist Reading Group from UTSOA Student ASLA”
Resonate: “A blog on what is currently Resonating with me.”
Saffron and Bear: “A serial fiction story about the adventures of a witch and her cat”
SATURNINE: “A weird scifi narrative in many, many pieces. Published monthly to the best of my ability.”
Serial Sinners: “A touch of excitement to get you through your week: daily erotica from indie authors delivered straight to your inbox.”
Spine & Arp: The Series: “A serial novel about a return to a crumbling New England town after the supposed end of the world, and the art school that's thriving in its dark heart.”
The Tempest and The Bloom: “A serial novel: literary fantasy”
Wrannaman: “Wrannaman's SciFi Books”