---
source: https://iinventedlight.com/library/notes/angular-inputs.md
title: "Angular component inputs accept data from a parent template"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "CC BY 4.0 (Angular docs, footer-verified); MIT (angular/angular source); prose restates cited source lines in own words"
license_family: angular-docs-ccby
attribution: "Summary by iinventedlight (AI-assisted). Sources: Angular docs, CC BY 4.0 text (angular/angular adev footer); Angular source, MIT (angular/angular). Notices: Angular documentation (angular/angular adev): Copyright (c) 2010-2026 Google LLC; CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Angular source (angular/angular): Copyright (c) 2010-2026 Google LLC; MIT (https://raw.githubusercontent.com/angular/angular/main/LICENSE)."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-11
status: published
approved_by: "Cole Withington, 2026-11-11 09:59 PT, Librarian chat widget t34s5: \"Yes, publish all 25 Angular and Vite drafts\""
checked_on: 2026-11-11
as_of: 2026-11-11
confidence: medium
untested: "No project was run for this note; only the fetched documentation and source files were read."
category: coding-references
topic_area: "code-web: Angular inputs"
tags: [angular, inputs, signals, components]
client: Librarian
sources:
  - id: S1
    title: "Component inputs"
    publisher: Angular docs
    url: https://angular.dev/guide/components/inputs
    accessed: 2026-11-11
    license: "CC BY 4.0"
  - id: S2
    title: "input() function"
    publisher: Angular source
    url: https://github.com/angular/angular/blob/main/packages/core/src/authoring/input/input.ts
    accessed: 2026-11-11
    license: "MIT"
---
# Component inputs accept data from a parent template

**Answer:** When you use a component, you commonly want to pass data into it. The child declares the data it accepts as inputs. You then bind to that property in a template. If you're familiar with other web frameworks, input properties are similar to props.

## The input function

The `input` function has special meaning to the Angular compiler. You can call it only in component and directive property initializers. It returns an `InputSignal`. You read the value by calling the signal. Signals created by `input` are read-only.

Input declarations are recorded statically at compile-time. Inputs cannot be added or removed at run-time. Input names are case-sensitive. When you extend a component class, the child class inherits the inputs.

If an input has no default and is not set, its value is `undefined`. Call `input.required` instead of `input` to declare a required input. Angular reports an error at build time if a required input is missing in a template.

## In source

The `input` function is how you declare inputs in directives and components. It also exposes `input.required` for required inputs.

## See also

- [angular-outputs](https://iinventedlight.com/library/notes/angular-outputs/)
- [angular-components](https://iinventedlight.com/library/notes/angular-components/)

## Claims

- id: C1
  claim: A component declares the data it accepts as inputs.
  source: S1
  evidence: "A component specifies the data that it accepts by declaring"

- id: C2
  claim: The input function returns a read-only InputSignal.
  source: S1
  evidence: "The `input` function returns an `InputSignal`."

- id: C3
  claim: Call input.required to declare a required input.
  source: S1
  evidence: "You can declare that an input is `required` by calling `input.required` instead of `input`:"

- id: C4
  claim: input declares inputs on directives and components.
  source: S2
  evidence: "The `input` function allows declaration of inputs in directives and"

## Sources

- [S1] Component inputs. Angular docs. https://angular.dev/guide/components/inputs . License: CC BY 4.0. Accessed 2026-11-11.

- [S2] input() function. Angular source. https://github.com/angular/angular/blob/main/packages/core/src/authoring/input/input.ts . License: MIT. Accessed 2026-11-11.


License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted). Sources and notices: Angular documentation (angular/angular adev): Copyright (c) 2010-2026 Google LLC; CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Angular source (angular/angular): Copyright (c) 2010-2026 Google LLC; MIT (https://raw.githubusercontent.com/angular/angular/main/LICENSE). Text was condensed and changed from the originals.

---

Agents: [/agents.md](/agents.md) | [/.well-known/agent-library.json](/.well-known/agent-library.json).