Love isn’t a battlefield. It’s a marketplace.

Lisa Bonos is Outlook’s assistant editor.

When a Harvard student named Gerry filled out a questionnaire for a new computer dating service in 1965, he was matched with six young women. He went out with two who lived nearby but didn’t contact the others.

One of those others — Nancy, an English major at Mount Holyoke — sent him a postcard that read simply: “Dear Gerry, Do you exist?”

Victor Kerlow for The Washington Post

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That note blossomed into weeks of correspondence and eventually a relationship. Nancy and Gerry married two years later, had a son and eventually divorced.

Their child, Dan Slater, grew up to become a journalist who, in his new book, “Love in the Time of Algorithms,” traces the history of computer-mediated matches, from the clunky system that brought his parents together to the sophisticated models of today’s dating Web sites.

Slater’s parents were ahead of their time; online dating didn’t explode as an industry until the 1990s and only recently shed its social stigma. Now, with about a third of singles dating online, it’s pretty clear that these daters do exist — even if they’re 20 pounds heavier or six years less educated than their profiles suggest.

So, as Valentine’s Day approaches, an updated version of Nancy’s question might be: Are you the best I can get?

I hope daters aren’t directly asking this of their matches. But two new books, Slater’s “Algorithms” and Amy Webb’s “Data, a Love Story,” suggest that succeeding in online dating, whether you’re the Web site making the matches or the person looking for them, is all about staying competitive.

It’s a tough marketplace out there. If you’re going to compete with these legions of singles, you ought to do some research to understand how your competitors are marketing themselves. And if you’re not a great date, or if the spark of marriage is fading, the Web promises plenty more where you came from.

On the business side of things, if a particular site doesn’t provide an enticing selection of singles and a type of matching that’s unique — such as ­OkCupid’s match percentages or ­eHarmony’s arduous screening process — daters will quickly move on.

Slater explains how competition affects dating on a macro level — how, for example, online dating companies market themselves and their algorithms to attract different kinds of daters. He delves into the world of niche sites, illustrating that, whether you’re an inmate, in the military or treating your sexually transmitted disease, there’s probably a site specifically for you — such as Meet-An-Inmate, MilitaryCupid or PositiveSingles. Locals, take note: The biggest market for the site Ashley Madison (slogan: “Life is short. Have an affair.”) is Washington.

But are these sites helping us settle down or keeping us uncommitted? The growth of sites promising to help you find The One, Slater reports, can make it harder for people to get into — and stay in — relationships. Think about it: Dating sites woo users by convincing them that their databases hold thousands of desirable people, and that courtship of the customer has a flip side, a tendency to make us wonder, “Hey, can I do better?”