In an epilogue called “The Return of Meaning,” Gleick argues that to understand how information gives rise to belief and knowledge, we have to renounce Shannon’s “ruthless sacrifice of meaning,” which required jettisoning “the very quality that gives information its value.” But Shannon wasn’t sacrificing meaning so much as ignoring it, in the same way that a traffic engineer doesn’t care what, if anything, the trucks on the highway are carrying. Once you start to think of information as something meaningful, you have to untether it from its mathematical definition, which leaves you with nothing to go on but the word itself. And in its ordinary usage, “information” is a hard word to get a handle on (even after a recent revision, the Oxford English Dictionary still makes a hash of its history). It’s one of those words, like “objectivity” and “literacy,” that enable us to slip from one meaning to the next without letting on, even to ourselves, that we’ve changed the subject.

That elusiveness is epitomized in the phrase “information age,” which caught on in the 1970s, about the same time we started to refer to computers and the like as “information technology.” Computers clearly are that, if you think of information in terms of bits and bandwidth. But the phrases give us license to assume that the stuff sitting on our hard drives is the same as the stuff that we feel overwhelmed by, that everybody ought to have access to, and that wants to be free.

Like most people who write about the information age, Gleick can’t avoid this semantic slippage. When he describes the information explosion, he reckons the increase in bytes, citing the relentless procession of prefixes (kilo-, mega-, giga-, tera-, peta-, exa-, and now zetta-, with yotta- in the wings) that’s mirrored in the proliferation of smartphones, tablets, game consoles and windowless server farms.

But there’s no road back from bits to meaning. For one thing, the units don’t correspond: the text of “War and Peace” takes up less disk space than a Madonna music video. Even more to the point, is “information” just whatever can be stored on silicon, paper or tape? It is if you’re Cisco or Seagate, who couldn’t care less whether the bytes they’re making provision for are encoding World of Warcraft or home videos of dancing toddlers. (Americans consume more bytes of electronic games in a year than of all other media put together, including movies, TV, print and the Internet.)

But those aren’t the sorts of things we have in mind when we worry about the growing gap between information haves and have-nots or insist that the free exchange of information is essential to a healthy democracy. Information, in the socially important sense — stuff that is storable, transferable and meaningful independent of context — is neither eternal nor ubiquitous. It was a creation of the modern media and the modern state (Walter Benjamin dated its appearance to the mid-19th century). And it accounts for just a small portion of the flood of bits in circulation.

Even so, there’s enough information coming at us from all sides to leave us feeling overwhelmed, just as people in earlier ages felt smothered by what Leibniz called “that horrible mass of books that keeps on growing.” In response, 17th-­century writers compiled indexes, bibliographies, compendiums and encyclopedias to winnow out the chaff. Contemplating the problem of turning information into useful knowledge, Gleick sees a similar role for blogs and aggregators, syntheses like Wikipedia, and the “vast, collaborative filter” of our connectivity. Now, as at any moment of technological disruption, he writes, “the old ways of organizing knowledge no longer work.”

But knowledge isn’t simply information that has been vetted and made comprehensible. “Medical information,” for example, evokes the flood of hits that appear when you do a Google search for “back pain” or “vitamin D.” “Medical knowledge,” on the other hand, evokes the fabric of institutions and communities that are responsible for creating, curating and diffusing what is known. In fact, you could argue that the most important role of search engines is to locate the online outcroppings of “the old ways of organizing knowledge” that we still depend on, like the N.I.H., the S.E.C., the O.E.D., the BBC, the N.Y.P.L. and ESPN. Even Wikipedia’s guidelines insist that articles be based on “reliable, published sources,” a category that excludes most blogs, not to mention Wikipedia itself.

Gleick wouldn’t deny any of this, but his focus on information as a prime mover and universal substance leads him to depict its realm as a distinct place at a remove from the larger social world, rather than as an extension of it. As he puts it, in the vatic tone that this topic tends to elicit, “Human knowledge soaks into the network, into the cloud” (more of those totalizing definite articles). In an evocative final paragraph, he pictures humanity wandering the corridors of Borges’s imaginary Library of Babel, which contains the texts of every possible book in every language, true and false, scanning the shelves in search of “lines of meaning among the leagues of cacophony and incoherence.” If it comes to that, though, we’ll have lots of help identifying the volumes that are worth reading, and not just from social networks and blogs but from libraries, publishers and other bulwarks of the informational old order. Despite some problems, a prodigious intellectual survey like “The Information” deserves to be on all their lists.