The Design of Everyday Things is a best-selling[1] book by cognitive scientist and usability engineer Donald Norman.

Originally published in 1988 with the title The Psychology of Everyday Things, it is often referred to by the initialisms POET and DOET.

It argues that although people are often keen to blame themselves when objects appear to malfunction, it is not the fault of the user but rather the lack of intuitive guidance that should be present in the design.

In the book, Norman introduced the term affordance as it applied to design,[3]: 282  borrowing James J. Gibson's concept from ecological psychology.

Examples of corresponding signifiers are flat plates on doors meant to be pushed, small finger-size push-buttons, and long and rounded bars we intuitively use as handles.

[7] He used the term to describe design based on the needs of the user, leaving aside, what he deemed secondary issues like aesthetics.

He went to great lengths to define and explain these terms in detail, giving examples following and going against the advice given and pointing out the consequences.

Jointly they thread the film through the projector and hold the free end, discussing how to put it on the takeup reel.

To do this, one must need to specify on how to move one's body, how to stretch to reach the light switch and how to extend one's finger to push the button.

A careful judgement is then passed on how the light has affected our world i.e. the room in which the person is sitting on the armchair while reading a book.

The formulation of the stages of evaluation can be described as: The difference between the intentions and the allowable actions is the gulf of execution.

The gulf of evaluation reflects the amount of effort that the person must exert to interpret the physical state of the system and to determine how well the expectations and intentions have been met.

[12] In the gulf of evaluation is the degree to which the system or artifact provides representations that can be directly perceived and interpreted in terms of the expectations and intentions of the user.

"[8]: 51–52 The gulf of evaluation applies to the gap between an external stimulus and the time a person understands what it means.

Both "gulfs" were first mentioned in Donald Norman's 1986 book User Centered System Design: New Perspectives on Human-computer Interaction.