Personal knowledge base

A personal knowledge base (PKB) is an electronic tool used to express, capture, and later retrieve the personal knowledge of an individual. It differs from a traditional database in that it contains subjective material particular to the owner, that others may not agree with nor care about. Importantly, a PKB consists primarily of knowledge, rather than information; in other words, it is not a collection of documents or other sources an individual has encountered, but rather an expression of the distilled knowledge the owner has extracted from those sources.

The term personal knowledge base was mentioned as early as the 1980s, but the term came to prominence when it was described at length in publications by computer scientist Stephen Davies and colleagues, who defined the term as follows:

The following classes of systems cannot be classified as PKBs:

PKM is similar to personal information management, but is a distinct topic based on the "information" vs. "knowledge" difference. PKBs are about recording and managing the knowledge one derives from documents, whereas PIM is more about managing and retrieving the documents themselves.

Non-electronic personal knowledge bases have probably existed in some form since the dawn of written language: Da Vinci's notebooks are a famous example. More commonly, card files and personal annotated libraries have served this function in the pre-electronic age.

Undoubtedly the most famous early formulation of an electronic PKB was Vannevar Bush's description of the "Memex" in 1945. Bush surveyed the post-World-War-II landscape and laid out what he viewed as the most important forthcoming challenges to humankind in The Atlantic Monthly. The Memex was a theoretical (never implemented) design or a system to help tackle the information overload problem, already formidable in 1945. In Bush's own words:

Consider a future device for individual use, which is a sort of mechanized private file and library. ... [A] device in which an individual stores all his books, records, and communications, and which is mechanized so that it may be consulted with exceeding speed and flexibility. It is an enlarged intimate supplement to his memory.

Bush envisioned collaborative aspects as well, and even a world-wide system that scientists could freely consult. But an important emphasis throughout the article was on expanding our own powers of recollection: "Man needs to mechanize his record more fully," he says, if he is not to "become bogged down...by overtaxing his limited memory". With the Memex, the user could "add marginal notes and comments," and "build a trail of his interest" through the larger information space. She could share trails with friends, identify related works, and create personal annotations. Bush's Memex would give each individual the ability to create, categorize, classify, and relate his own set of information corresponding to his unique personal viewpoint. Much of that information would in fact consist of bits and pieces from public documents, just as the majority of the knowledge inside our own heads has been imbibed from what we read and hear. But the Memex also allowed for the specialized recording of information that each individual perceived and needed to retain. The idea of supplementing our memory" was not a one-size-fits-all proposition, since no two people have the same interests, opinions, or memories. Instead, it demanded a subjective expression of knowledge, unique to each individual.

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