Function is the purpose or role that a designed object is intended to serve. A door handle functions to open a door. A website functions to deliver information or enable a transaction. A logo functions to identify a brand. Function is the job. Form is how the job gets done. The two are inseparable in good design. A beautiful chair that collapses when you sit on it has failed. A functional chair that is painful to look at has also failed, though less dangerously.

Function in design is not just about utility. It includes usability, accessibility, and emotional function. A product can work perfectly and still frustrate the user. A website can load fast and still be confusing. Functional design considers the whole experience. Can the user find what they need? Can they complete the task? Do they feel confident doing it? Emotional function matters too. A luxury product should feel luxurious. A children's toy should feel playful. The form should express the function and the feeling. The Bauhaus principle "form follows function" captured this idea. The shape of an object should be determined by its purpose. That principle has been debated for a century. Some designers argue that form can lead function, creating new possibilities. Others insist that function must come first. The debate continues because both perspectives have merit. The best design often achieves both.

Function in design

• Utility — does it do the job
• Usability — is it easy to use
• Accessibility — can everyone use it
• Emotional — does it feel right
• Durability — does it last

Function is the reason a design exists. Everything else supports it.