component

A component groups code that performs one recognizable function. Other parts of the software do not need to know exactly how it works internally. They use the component through agreed inputs and outputs. This allows a large system to be assembled from smaller parts that are easier to understand.

From a button to a complete service

The size of a component depends on the context. In a frontendGlossary · In brieffrontendThe frontend is the part of a website or application that users see and operate, such as pages, buttons, forms and interactive screens.Read more, a button, form or table can be a component. An interface component often defines both its appearance and its behaviour. In a backendGlossary · In briefbackendThe backend is the part of an application that processes data, applies business rules and communicates with other systems on the server. Users usually access it through a frontend or API.Read more, a component might process payments, generate documents or check user permissions.

Components can call each other directly or exchange data through an APIGlossary · In briefAPIAn API is a defined way for software to exchange data or call functions in other software without needing to know how that software works internally.Read more. Well-chosen boundaries clarify which part is responsible for each task. This makes a component easier to develop, test or replace separately. It does not mean every component can run independently: many still depend on the application in which they are used.

Component, module or service?

These terms overlap but emphasize different things. A module usually groups code within a program. A service performs a defined task and often runs as a separate process accessible over a network. Component is the broader term: both a module and a service can be considered components of a larger system.

The name says more about the part's role than its technology. What matters is that it has a recognizable task and clear agreements with the other parts.