To put a literary spin on an adage: If you read a book but don’t post about it on social media, did you really read it?

On Bookstagram, a niche corner of Instagram, readers share dazzling photos of single books, stacks of books, coffee and books, nature and books. Books that never looked so good. And on YouTube’s BookTube, bibliophiles upload vlogs, or video logs, anywhere from a couple minutes to more than an hour long. Some BookTubers specialize in spirited reviews; there’s an account that posts live-action illustrations of C.S. Lewis essays, and another that analyzes the classics in gangster-speak.

In these sprawling but welcoming communities, readers have found one another, banding together in a global, aesthetically pleasing book club that’s open for discussion 24/7. More than 33 million Instagram posts are tagged “#bookstagram,” and BookTube videos can amass millions of views — luring publishers and authors who actively court the most popular accounts. We asked three ’grammers and ’tubers — otherwise known as book influencers — to describe their experiences in these online communities that are so warm, they feel like social media’s best.

Name: Jamise Harper, 50, Washington

Follower count: 9,000

Where to find her: @spinesvines on Instagram

Moments after Harper popped into a Baltimore bookstore last summer, she was greeted by an enthusiastic patron: “‘Oh my gosh, are you Spines and Vines?’ ” she recalls a woman gushing. “And my son was like, ‘You’re famous!’ ”

Harper is, indeed, Spines and Vines. She joined Bookstagram and adopted the moniker in 2015, an ode to her two loves: books and wine. Her near-daily photos are colorful — stacks of brightly hued books next to a glass of her favorite vino, usually rosé, or paired with gooey s’mores or chicken nachos. Many of the photos are accompanied by reviews: five wineglass emoji for “Miracle Creek” by Angie Kim; four for Tayari Jones’s “Silver Sparrow.”

From the beginning, Harper focused on reading books by women, and in 2018, she created the #diversespines initiative — a hashtag that’s been used nearly 10,000 times to indicate a book by a woman of color. “It blew up quickly,” she says. “I had booksellers telling me they follow the hashtag to know what people are reading and what to stock, and so many people say they use it as a resource to pick out what they’re going to read next.”

The online community has led to real-life community: Harper co-founded a popular monthly D.C. book club with fellow Bookstagrammer Lupita Aquino (@Lupita.Reads), and she recently launched a quarterly dinner meetup at a local bookstore. “You have the same common love for something, and that binds you together,” she says of the friends she’s made. “I think it’s remarkable.”

Name: Cindy Pham, 24, Norfolk

Follower count: 33,500

Where to find her: @readwithcindy on YouTube

In a recent 35-minute video, Pham blasted one of her summer reads as “stupid . . . and neurotic ramblings,” praised another as “the book version of comfort food” and analyzed literary fiction as a genre.

The funny, fast-talking book lover launched her YouTube channel, Read With Cindy, a year ago. She posts a new video about once a week, ranging from in-depth reviews to satiric rants on book culture.

Pham assigns each title she discusses a rating of 1 to 5 — and given that her videos collect more than 10,000 views, she takes those scores seriously. “When I started, my intention was just doing commentary and making stupid jokes about the books I was reading,” she says. But as her following grew, many readers told her they used her analysis to decide what to read next. “So I started reading more critically, and now it’s become a balance of humor and critical thoughts.”

Pham’s videos attract an international audience; during a recent trip to Portugal, she arranged to meet a handful of readers who subscribe to her videos. Before launching her BookTube channel, she had made only a few videos, mostly for school. It’s a low-budget endeavor, Pham says: “I just sit in front of a white wall and prop my phone on a stack of boxes” — creating the intimate feeling that you’re lounging in the living room with her, talking books.

Name: Jordan Moblo, 35, Los Angeles

Follower count: 21,500

Where to find him: on Instagram

There’s a popular Instagram hashtag called #bookstagrammademedoit: If you don’t speak hashtag, that’s “bookstagram made me do it,” or a title one never would have selected if not for being flooded with gorgeous pictures of its cover. For Moblo, that’s one of the joys of Bookstagram. He once shrugged off John Boyne’s “The Heart’s Invisible Furies,” but then it became one of his favorite books — all because, you know, Bookstagram made him do it.

Moblo joined Bookstagram a year ago, after a book-filled vacation inspired him to track his reads. At the time, he was logging seven or eight books a year. Now, he’s completing three to five a week; at the end of June, his count for the year was 81. On a recent Tuesday, 24 hours before heading to Africa for his honeymoon, Moblo had packed 13 books and lamented that Bookstagram has thoroughly complicated his luggage situation.

African scenery aside, most of Moblo’s photos land in three groups: flat lays (plants, coffee and groups of books, taken from above); stacks showing off the titles’ spines; and a single book on a neutral surface, always accompanied by a review, along with a list of similar books or read-this-instead suggestions.

Bookstagram, Moblo says, has become his favorite creative outlet. “It’s very quirky — you find there are all these little worlds,” he says. “I’m finding new books, I feel like I’m getting an education in authors I wouldn’t normally read, and I’m making friends I stay in touch with on a daily basis. There are so many ways of using this to your advantage.”

Angela Haupt is a freelance writer and full-time health editor in the District.