Not to state the obvious, but a design is a type of plan to create something. When we think of design, we typically we think of drawing up blueprints for a physical product, like the consumer-favourite IKEA Pöang chair.
But that’s not always the case — you can actually design plenty of things that don’t exist in the physical realm as well: like organizations, systems, digital images or software, or anything else really.
Designing something typically involves drawing up diagrams of the end product and a list of specifications (aka ‘specs’). This list of “specifications” is used to communicate the design to people within a company who build the end product and test it (and also the people who advertise and sell it).
A specification is kind of similar to a description. A list of design specs is kind of like a rubric: a list of criteria and descriptions that tell you what a successful end product should look like.
There are lots of types of specifications, such as Requirement specs, Functional specs, Design specs, Material specs, Test specs, Performance specs, and Quality specs.
Requirement specs might be general description of what the product does, like “the Poäng chair must be aesthetically pleasing, lightweight, and be appropriate for adults to sit in.” or for a refrigerator: “must keep refrigerated foods cold enough to maintain food quality until their expiry dates”.
The requirement could also be more specific, which is sometimes called a functional specification or performance specification.Functional specs or performance specs tell us specifically what “functional”ability it must have, not how it has the ability. For example: The Poäng chair’s backrest must be long enough to support the entire length of an average adult’s back. This tells you how the chair needs to function, not what specific properties of the chair allow it to do so. For a refrigerator, a functional spec might be: the air temperature inside the body of the fridge must stay at 5°C, unless the door is open.
Design specs usually describe the specific properties of the product that will satisfy a requirement or function. For example: The Pöang chair backrest will be 80cm long (this design spec fulfills the requirement of supporting the average adult’s back).
Material specs outline all the properties of the materials used in the product. For example: how strong or heavy the wood used in the chair is.
Test specs tell you what features of the product are going to be tested. For each feature’s that’s going to be tested, we also need to specify exactly what we’d need to see to say the product has “passed” the test for that feature. A simple example: The chair’s backrest is a feature that we need to test. The chair’s backrest doesn’t break when we apply 100kg of weight to it 200,000 times. In this example, we would also draw up a diagram showing what kind of apparatus we’re going to use to apply the force to the backrest.