Finding a mate used to be a long quest that drew upon the aid of family, friends and co-workers to uncover a few people who might be date-worthy. Relationship websites now offer hundreds of potential mates at a keystroke. …

This is all rich anthropological loam, and in “Love in the Time of Algorithms” journalist Dan Slater has dug in manfully to explain how technology is transforming how we meet and fall in love. The guiding principle of his book is that anyone who wants a happy relationship deserves one, and if online dating is the means to obtaining it, so be it. Meeting online may not be what Hollywood calls a “meet cute,” but it is increasingly common.

Along with introducing readers to the many men and women looking for romance online, Mr. Slater recounts the accomplishments of the entrepreneurs who have profited from computerized dating services over the past half a century—an exotic and often sharp-tongued bunch.

In 1964, Jeff Tarr, an undergraduate mathematician at Harvard, was so desperate to meet girls that he struck upon the idea of composing and distributing dating questionnaires, which he then fed into an IBM computer the size of a large bookcase, in order to match men and women at colleges across New England. …