To scholars, the ready access to updated information online is a net gain for the public. But that doesn’t mean that they can’t mourn the passing of a household icon  a set of knowledge-packed books on their own reserved shelves that even parents had to defer to.

“I remember in my own childhood in the 1940s, early ’50s, I and my parents would sit around the table and look at the encyclopedia together,” said Larry Hickman, director of a center at Southern Illinois University devoted to the education pioneer John Dewey. “In the old days, the Encyclopaedia Britannica or the World Book encyclopedia was regarded as authoritative,” he recalled, laughing as he agreed, “That’s why you would copy it for your book report.”

But Mr. Hickman said that parents and children can have the same discussions “seated in front of the computer, the electronic hearth, as I like to call it.” And he said that losing a set of books considered infallible was actually a good thing for developing critical thinking.

Yet, as encyclopedia publishers struggle, the Internet age has become a golden one for the newer kind of encyclopedia.

An ambitious project to catalog online all known species on earth  with the even-more-ambitious title the Encyclopedia of Life  went live last month. The Stanford Encyclopedia of Philosophy, a project that began online in 1995 and has never been in print and never will be, is chugging along with nearly 1,000 entries that are vetted by an academic board of more that 100 scholars for a total of 10 million words.

And then there is the behemoth Wikipedia, a project that has no board to vet articles and is created by thousands of volunteers, with more than two million articles in English and an additional five million in a babel of other languages.

Wikipedia is regularly among the top 10 most visited sites on the Internet throughout the world  maybe in part because there’s a lot more there than meets the needs of the average term paper. The superabundance of less-than-prized information on the site has led to a phenomenon called “wiki-groaning,” which involves comparing the length of seemingly disparate articles to humorous effect. Lightsaber Combat beats out Modern Warfare, for example, and John Locke, the character from the TV show “Lost,” edges out the other John Locke, whoever he was.