Obfuscation may be used for many purposes. Doctors have been accused of using jargon to conceal unpleasant facts from a patient; American author Michael Crichton claimed that medical writing is a "highly skilled, calculated attempt to confuse the reader".B. F. Skinner, noted psychologist, commented on medical notation as a form of multiple audience control, which allows the doctor to communicate to the pharmacist things which might be opposed by the patient if they could understand it. Similarly text-based language, like some forms of leet, are obfuscated to make them incomprehensible to outsiders.
"Eschew obfuscation", also stated as "eschew obfuscation, espouse elucidation", is a humorous fumblerule used by English teachers and professors when lecturing about proper writing techniques. Literally, the phrase means "avoid being unclear" or "avoid being unclear, support being clear", but the use of relatively uncommon words causes confusion, making the phrase an example of irony, and more precisely a heterological. The phrase has appeared in print at least as early as 1959, when it was used as a section heading in a NASA document.
An earlier similar phrase appears in Mark Twain's Fenimore Cooper's Literary Offenses, where he lists rule fourteen of good writing as "eschew surplusage".