I just read the book 'Don't make me think' by Steve Krug. But I had the trouble understanding the difference between self-evident and self-explanatory.

Could someone please make it clear for me, or provide an example to explain it?

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Self-evident: The thing, itself, is evidence of itself

(Here, the woman, herself, is evidence of her pregnancy, and the unborn baby is evidence of itself in the form of the "baby bulge".)

Pregnant woman's belly (source)

Self-explanatory: The thing explains itself

(Here, the pregnancy test stick includes an explanation of how it should be read.)

Woman holding a positive pregnancy test (source)

  • +1, but to be clear: in the first case it is her pregnancy that is self-evident; in the latter it is her pregnancy test that is self-explanatory. – ruakh Sep 3 '16 at 21:42
  • Yes, @ruakh is right. The woman in the first image is, herself, evidence of her pregnancy; in the second image, the test-stick explains itself. – 1006a Sep 4 '16 at 0:43
  • Wow..These two pictures include thousands of words. Why can't I think up this kind of simple example? ++++++++++1 – Joe.wang Sep 5 '16 at 1:52
  • Here's why you had to edit the answer recently: meta.english.stackexchange.com/questions/10020/… – NVZ Feb 16 '17 at 2:52
  • Thanks for the explanation, @NVZ. It did seem a little random. – 1006a Feb 16 '17 at 3:20

The ideas are similar. Here are the definitions:

Self-evident adjective Not needing to be demonstrated or explained; obvious: self-evident truths - ODO

Self-explanatory adjective Easily understood; not needing explanation: the film’s title is fairly self-explanatory - ODO

These are derived from the following words:

Evident adjective Clearly seen or understood; obvious: she ate the biscuits with evident enjoyment - ODO

Explanatory adjective Serving to explain something: explanatory notes - ODO

The term self-evident refers to things like truths, ideas or functions that are 'obvious'. (Note: what's obvious to one might not be obvious to another, but that's a different topic).

We call something self-explanatory if there isn't any further explanation required, other than what the thing itself provides.

For example, consider this from the (American) Declaration of Independence:

We hold these truths to be self-evident, that all men are created equal, ... - archives.gov

It holds that the truth all men are created equal is self-evident, meaning that it's obvious that all men are created equal. It simply states the equality but doesn't explain why there is equality, so the statement isn't self-explanatory.

Now consider a street sign that says,

No Parking

This sign is self-explanatory. The sign itself explains why it was put there - to prohibit parking in that location. We wouldn't call the sign self-evident because the sign isn't a truth, idea or function.

In relation to the use of the terms in your book, here's a useful commentary that references the book:

As website designers and developers, we always strive to deliver experiences that any website visitor can easily understand without investing additional thought. Some might call this "self-explanatory;" but it isn't. Regular folks (like you) shouldn't have to re-read or self-explain anything in order to understand it — they should just get it. It's called "self-evident."

Steve Krug's book, "Don't Make Me Think!" breaks it down in plain English, and explains how important this idea is to designing a successful website. The average internet user spends very little time on any given web page, they want to find what they are looking for quickly, and they don't want to, well, think.


Think of a door, for example. If it is designed properly there is no need for a sign that reads 'push' or 'pull' on either side. This is what we strive for with the level of usability of our website designs.

- John Rogers, Self-Explanatory vs. Self-Evident Web Design

The distinction drawn between the terms here is that good design shouldn't just be self-explanatory (e.g. have good signs) - good design should make the purpose self-evident (you look at it, and just know).

For example, consider controls on a user interface. Buttons labelled "page up" and "page down" are self-explanatory. The function of a properly-positioned scroll-bar is self-evident.

  • Wonderful Explanatory. You opened my eyes to see something. Can't upvote twice. Thank you very much and easy understanding example. especially in the UX. – Joe.wang Sep 2 '16 at 10:48
  • @Joe.wang Glad it helped. :) – Lawrence Sep 2 '16 at 10:58
  • 3
    John Rogers' quote obscures the fact that self-evident can only be applied to (statements of) facts while self-explanatory can only be applied to (possibly immaterial) things. A web-page cannot be self-evident, although it's purpose can very well be. In that case the page is self-explanatory. A game may be self-explanatory; in that case its rules are (self-) evident. – Peter A. Schneider Sep 2 '16 at 17:55
  • 1
    +1 @PeterA.Schneider Indeed, and thank you. I suppose the subtle formatting in the last paragraph of my answer wasn't sufficiently self-explanatory in this regard. :) – Lawrence Sep 3 '16 at 0:07
  • Be careful with the "truthiness" of quoting the USA's Declaration of Independence, particularly that line. Remember that slavery was legal and widely accepted, so the definitions of "men" and/or "equal" were different from current context or it's actually a rhetorical piece ignoring the "truth" in the statement. – user2943160 Sep 3 '16 at 15:27

Both are terms for something which seems obvious without further input. Something that is self evident is obvious on its own, while something which is self explanatory is obvious, because it documents itself as true. Now, that has been said several ways, and still may not be clear, because the two are close in meaning, so let's try by example. You are on a plane and there is a lavatory:

The door is open, you can see in. As you can see for yourself if there is anyone in there, it is self evident if the lavatory is occupied or not.

The door is closed, so you cannot see in. But there is a label on the door that says occupied or vacant. This lavatory is self explanatory in letting you know if it is occupied or not.

  • 1
    More concisely: An open, unoccupied lavatory is self-evident. An occupied lavatory with a sign saying "occupied" is self-explanatory. – Wildcard Sep 2 '16 at 23:39

According to Dictionary.com,

self-explanatory (adjective)

  • explaining itself; needing no explanation; obvious.

It basically means that whatever that is defined doesn't require addition information to convey its meaning.


  • These rules are so simple; they are self-explanatory.
  • The book titled "History of the Internet" is self-explanatory, however, the book "Stormbreaker" isn't.

self-evident (adjective)

  • evident in itself without proof or demonstration; axiomatic.

This means that the fact that is stated doesn't require additional proof to claim its truth.


  • He's not a native English speaker, well that's self-evident.
  • The claims they make are self-evident; there is no further investigation needed to close the case.

Note: the British definition states that they are both the same -- synonymous in practice.


They both adjective and usually interchangable. But self-evident is a higher degree of its meaning than self-explanatory.

According to Merriam-Webster

Self-evident Adjective : Clearly true and requiring no explanation(evident without proof or reasoning)

Self-explanatory Adjective : Easy to understand without explanation(explaining itself: capable to understand without explanation)

P/s: You'd better install Merriam-Webster on your smartphone. It's a concise-content dictionary yet easy to understand.

  • I beg to disagree with the conclusion you draw from the quotes. Explanatory concerns understanding; evident concerns truth. Understanding is about procedures, things; truth is about already-understood facts and statements. That all men are created equal is not self-explanatory; it is not about understanding a complex mechanism, procedure or web site. The question is whether that very simple fact it is true, and the word for that is evident. – Peter A. Schneider Sep 2 '16 at 18:01

A more concise explanation:

A self-evident fact is obvious simply by looking.

A self-explanatory object explains itself if you look at it.


The purpose of a chair in a waiting room is self-evident.

A sign saying "please wait here to be seen" is self-explanatory.

A fact can be self-evident. A fact cannot be self-explanatory.

An object such as a sign or a labelled button can be self-explanatory. All objects are self-evident.

(You see the object is there by looking at it, so it is self-evident. The purpose of the object may not be self-evident.)


I think the difference between them is the difference between the words evidence and explanation. You would say self explanatory when an explanation would be called for if it wasn't so obvious. If the fishbowl is broken on the wet floor, and cat-paw-shaped footprints are leading away, it's self explanatory how this happened. If someone speaks with a thick accent, it's self evident that they're not a native speaker.

  • 1
    While your premise is correct, your fish bowl example exemplifies self-evident, not self-explanatory. – Chenmunka Sep 2 '16 at 12:12

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