Component
A component is an individual unit of software that performs a specific function and can be developed, tested, or reused independently.
“A part of a system that can be tested in isolation.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Component?
Components are the building blocks of software systems. Examples include classes, modules, services, or libraries depending on the system architecture.
Independent unit: Components perform defined responsibilities within the application.
Reusable design: Components may be reused across multiple systems or projects.
Testing focus: Components are verified during component testing before integration.
Real World Example
An insurance claims platform is connecting a claim intake service, a policy validation service, and a payment approval service.
Each part can look correct in isolation while the handoff between parts still fails. Component helps testers focus on the boundary where data, timing, and responsibility meet.
The tester checks payloads, error handling, retries, missing fields, and the order of service calls instead of only confirming that each screen appears.
The claims flow becomes more dependable because Component exposes defects that only appear when real components collaborate.
Practice Questions
Question 1
Which description BEST fits a component?
Question 2
Which practice MOST helps component testability?
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