User Experience
Edge Case
Plain English
Unusual situations that still need handling.
Definition
An edge case is a rare or extreme scenario that falls outside typical glossaryUser BehaviourUser behaviour refers to how users interact with a product, including actions, patterns, and decision-making processes.Open glossary term.
In practice
Considered during design and development to ensure robustness.
In context
The label is often wrong. A case affecting two per cent of users on a glossaryServiceA service is a component or function that performs a specific task within a system.Open glossary term with a million of them is twenty thousand people, and they will all contact support.
The reality
Often ignored until they cause issues in production.
Compared with
Edge Case vs Happy Path
The glossaryHappy PathThe happy path is the ideal user journey where everything works as expected without errors.Open glossary term is the expected route with no complications. An edge case is a rare or extreme situation outside it. Edge cases are where products lose glossaryTrustUser confidence that a product, service, or organisation will do what it promises.Open glossary term, because they arrive at exactly the moment the user needed it to work.
FAQ
Common questions
A few practical answers to the questions that usually come up around this term.
What is an edge case?
A rare or extreme scenario.
Why are edge cases important?
They prevent unexpected failures.
When should they be considered?
During design and development.
What is a common mistake?
Ignoring them.
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