KISS principle

Key takeaways

KISS principle belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect KISS principle to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of KISS principle from memory before moving on to harder problems.

Reference excerpt

KISS ("Keep it simple, stupid") is a design principle first noted by the U.S. Navy in 1960. First seen partly in American English by at least 1938, KISS implies that simplicity should be a design goal. The phrase has been associated with aircraft engineer Kelly Johnson. The term "KISS principle" was in popular use by 1970. Variations on the phrase (usually as some euphemism for the more churlish "stupid") include "keep it simple, silly", "keep it simple and straightforward", "keep it simple, soldier", and "keep it simple, sweetie".

Origin The acronym "Keep it simple, stupid" was reportedly coined by Kelly Johnson, lead engineer at the Lockheed Skunk Works (creators of the Lockheed U-2 and SR-71 Blackbird spy planes, among many others). However, the variant "Keep it Short and Simple" is attested from a 1938 issue of the Minneapolis Star. While popular usage has transcribed it for decades as "Keep it simple, stupid", Johnson transcribed it simply as "Keep it simple stupid" (no comma), and this reading is still used by many authors. The principle is best exemplified by the story of Johnson handing a team of design engineers a handful of tools, with the challenge that the jet aircraft they were designing must be repairable by an average mechanic in the field under combat conditions with only these tools. Hence, the "stupid" refers to the relationship between the way things break and the sophistication available to repair them. The acronym has been used by many in the U.S. military, especially the U.S. Navy and United States Air Force, and in the field of software development.

Variants The principle most probably finds its origins in similar minimalist concepts, such as:

Occam's razor; "Simplicity is the ultimate sophistication"; Shakespeare's "Brevity is the soul of wit"; Mies van der Rohe's "Less is more"; Bjarne Stroustrup's "Make Simple Tasks Simple!"; Dr. Seuss's ode to brevity: "So the writer who breeds more words than he needs, is making a chore for the reader who reads"; Johan Cruyff's "Playing football is very simple but playing simple football is the hardest thing there is"; Antoine de Saint-Exupéry's "It seems that perfection is reached not when there is nothing left to add, but when there is nothing left to take away"; Colin Chapman, the founder of Lotus Cars, urged his designers to "Simplify, then add lightness"; Attributed to Albert Einstein, although this may be an editor's paraphrase of a lecture he gave, "Make everything as simple as possible, but not simpler"; Steve Jobs's "Simplify, Simplify, Simplify", which simplified Henry David Thoreau's quote "Simplify, simplify, simplify" for emphasis; Northcote Parkinson, British academic and sometimes military officer and military critic, expressed this idea as "Parkinson's Third Law" (c. 1957): "Expansion means complexity and complexity, decay; or to put it even more plainly—the more complex, the sooner dead"; Heath Robinson contraptions and Rube Goldberg's machines, intentionally overly-complex solutions to simple tasks or problems, are humorous examples of "non-KISS" solutions.

Usage

In film animation Master animator Richard Williams explains the KISS principle in his book The Animator's Survival Kit, and Disney's Nine Old Men write about it in Disney Animation: The Illusion of Life, a considerable work of the genre. The problem faced is that inexperienced animators may "over-animate" in their works; that is, a character may move too much and do too much. Williams urges animators to "KISS".

In software development Don't repeat yourself (DRY) Minimalism Unix philosophy Arch Linux Slackware Linux Chartjunk List of software development philosophies Reduced instruction set computing Rule of least power There's more than one way to do it Worse is better (Less is more) You aren't gonna need it (YAGNI)

In politics Keep It Simple Solutions, New Brunswick, a minor political party in New Brunswick, Canada Keep It Straight and Simple Party, a minor political party in South Africa

In popular culture In the Filipino neo-noir film Segurista, KISS is invoked by Mrs Librada (played by Liza Lorena) as an approach to selling insurance. In the American version of The Office, Michael Scott's advice to Dwight Schrute before making any decision is KISS (Keep it Simple, Stupid).

See also BLUF (communication) Concision Elegance The Fox and the Cat (fable) It's the economy, stupid Mini survival kit Muntzing Perfect is the enemy of good Simple living Ultralight backpacking

References

External links

Illustrations

Worked examples

Example 1 — a first encounter with KISS principle

Start with the simplest possible case. Write down what KISS principle claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to KISS principle before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about KISS principle ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of KISS principle

In research: KISS principle appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses KISS principle in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: KISS principle is common in secondary-school and first-year university syllabi. It links to neighbouring topics Adages, Computer jargon, Design, so understanding it makes those chapters shorter.
In everyday life: Look for KISS principle outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study KISS principle in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what KISS principle means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain KISS principle out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is KISS principle in simple terms?

KISS ("Keep it simple, stupid") is a design principle first noted by the U.S. Navy in 1960.

Why does KISS principle matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study KISS principle?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on KISS principle.