White knowledge is information you acquire without effort, or information that you pick up without being able to remember how you know something. The term was likely coined by science fiction/fantasy author, Terry Pratchett, in his Discworld series of books. First usage may date to 1995 or earlier, depending upon accounts.
Due to the popularity of Pratchett’s humorous series, the concept of white knowledge came into the mainstream of the English language, and was most commonly used at first by people working in the information technology (IT) field, though it might have been used by any fans of Pratchett’s books. White knowledge also may have first been used in the UK, and migrated quickly to the US and Canada.
Most people have the experience of realizing they just know something, or they’ve learned something along the way, picking it up in the constant buzz of communication that surrounds them. The term may be related to white noise, the background sounds on television and radio channels that aren’t receiving a signal.
The constant stream of communication in which people live helps us learn things without being conscious that we’re learning them. Certain types of lingo like slang words, for instance, or all of the acronyms used in texting are often white knowledge acquirements. Most people don’t sit down and study these acronyms: they just pick them up in the process of texting, and if they’re easily learned, they’re examples of white knowledge.
Other types of white knowledge could be picked up in working environment: slang terms for various types of production, abbreviations or alternate names for food ordered in restaurants, informal code names for patients in hospitals. In other situations, people simply “know” certain things, like how to say a particular prayer at church, or that slavery existed in America. Cultural incidences that mention things like slavery make them common knowledge, and most kids are familiar with the concept of slavery long before they take an American history course.
Sometimes white knowledge can refer to specifically to fantasy or science fiction works. For instance, Robert Jordan, though he likely doesn’t use Pratchett’s term, uses the concept repeatedly in the The Wheel of Time series. People learning to channel, Jordan’s term for using magic, have these incidents where they suddenly just know how to weave the powers to produce a result, without being taught.