Witt’s move to San Francisco in 2012 coincides with her temporary experiment in alternative sexuality before what she assumes will be her monogamous future. “The thought of not having examined the possibilities filled me with dread,” she writes. So Witt examines them with gusto, including an orgy featuring a “spanking train” and “electrified wand,” organized in part by a charming 20-something woman in a polyamorous marriage. (Witt also attends her wedding, where the officiant says: “By the power invested in me by the internet, you are now married. You can kiss each other and other people.”)

When not attending orgies and polyamorous weddings, Witt visits orgasmic meditation classes, BDSM pornography film shoots and insular communities of webcam enthusiasts. Though Witt initially positions “Future Sex” as a journey of self-discovery, I found that to be the least satisfying part of her book. Very little of what Witt tries turns her on, and she ends the journey in much the same place she begins — introspective and breathtakingly honest, but seemingly still uncertain about her sexual future.

If Witt struggles at times as a memoirist, she succeeds as a meandering journalistic voyeur, one with a deeply empathetic and nuanced appreciation of sexual renegades and outcasts. Though “Future Sex” isn’t as much about the future as its title suggests, it is a smart, funny, beautifully written account of contemporary women trying to understand their sexual desires — and fashion physically and emotionally safe ways to express them.

Witt introduces us to a broad cast of memorable women. In a chapter focused on the webcamming site Chaturbate, for example, Witt meets Wendy, an introverted 44-year-old artist from Iowa who relishes the “mass intimacy” of Chaturbate and who finds community, meaning and sexual satisfaction by helping guide “people through their masturbatory fantasies.” There’s Karaste, a large-breasted webcam performer who says she only felt good about her body once she got on the internet. Without it, Karaste suspects, she “would have been reading Good Housekeeping and working out how to fake an orgasm better.” Then there’s Edith, a 19-year-old college student and popular performer on the site who describes herself as “internet sexual,” quotes Albert Camus during her cam sessions and masterfully makes each male viewer “feel as if he and only he were the person who might understand and rescue her from both her tortured soul and her vow of celibacy.”

Speaking of men, Witt finds them less interesting to watch on Chaturbate. They invariably recline on a computer chair in a dimly lit room, the camera aimed at their crotch. “It was amazing,” Witt writes, “the diversity of what men wanted performed for them and how little they offered to others, except for a few of the gay guys, who seemed to understand that some form of flirtation might exhilarate the spirit.”