# lock key

> computer key that toggles application state

**Wikidata**: [Q3532816](https://www.wikidata.org/wiki/Q3532816)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Lock_key)  
**Source**: https://4ort.xyz/entity/lock-key

## Summary
A lock key is a physical button on a computer keyboard that toggles a specific application or input state, such as Num Lock or Caps Lock. These keys modify how other keys on the keyboard function.

## Key Facts
- Classification: Lock key is a subclass of computer key.
- Primary Function: Toggles the state of an application or input feature (e.g., enabling/disabling number pad, capital letters).
- Related Keys: Includes Num Lock, Caps Lock, Scroll Lock, Shift Lock, and F-Lock.
- Presence: Has entries in 6 Wikipedia languages (English, French, Japanese, Korean, Tatar, Chinese).
- Sitelink Count: Featured on 6 different Wikimedia sites (including Wikipedia).
- Freebase ID: /m/0cdzdd
- Category: Belongs to the category "Lock keys".

## FAQs
### Q: What is the purpose of a lock key?
A: A lock key toggles a specific state on the keyboard, such as making number keys input numbers instead of moving the cursor (Num Lock) or making letter keys always uppercase (Caps Lock). This modifies the keyboard's behavior until toggled off.

### Q: How is a lock key different from a regular modifier key like Shift?
A: Lock keys (e.g., Caps Lock) change the *persistent state* of keys, affecting their output until the lock is released. Modifier keys like Shift change the output *only while they are held down*.

### Q: Why do some lock keys like Scroll Lock have limited use today?
A: Lock keys like Scroll Lock were designed for specific, now-legacy applications or terminal environments. Modern operating systems and software often ignore or rarely utilize these older lock states.

### Q: Are lock keys essential on a modern keyboard?
A: Yes, Num Lock is essential for using the separate numeric pad effectively. Caps Lock remains useful for typing large amounts of uppercase text without holding Shift. Other lock keys are less critical today.

## Why It Matters
Lock keys are fundamental to keyboard input efficiency and user experience. They provide a persistent state toggle, allowing users to work efficiently with features like the numeric pad or input blocks of text without needing to hold modifier keys continuously. By modifying the behavior of other keys, lock keys solve the problem of input mode switching directly on the keyboard itself, streamlining tasks from data entry to text formatting. While some historical lock keys have faded in relevance due to technological changes, core lock keys like Num Lock and Caps Lock remain indispensable tools for millions of users, directly impacting productivity and accessibility.

## Notable For
- **State Toggling Function:** Primarily defined by its core function of toggling the persistent state of an application or input feature on a computer.
- **Keyboard Classification:** Uniquely categorized as a specific type of "computer key," distinct from letter, number, function, or modifier keys.
- **Multiple Instances:** Represents a class of keys encompassing several distinct physical keys on standard keyboards (e.g., Num Lock, Caps Lock).
- **Ubiquity:** Standard feature on virtually all IBM-compatible (PC) keyboards, making lock keys one of the most common and recognizable keyboard categories for users.

## Body
### Definition
A lock key is a specific type of computer key. Its defining characteristic is its ability to toggle a persistent application or input state. Pressing a lock key changes the behavior of other keys until the lock key is pressed again.

### Common Types
- **Num Lock:** Toggles the function of the numeric keypad keys between inputting digits and acting as cursor control keys (Arrow, Home, End, etc.).
- **Caps Lock:** Toggles the input of letter keys between lowercase and uppercase. When active, all alphabetic keys produce uppercase letters without needing to hold Shift.
- **Scroll Lock:** Historically used to toggle the behavior of arrow keys in text editors to scroll the window instead of moving the cursor. Its use is now rare in modern applications.
- **Shift Lock / Caps Lock (Historical):** Shift Lock functioned similarly to Caps Lock, affecting Shift-key behavior, but is largely obsolete and integrated into the modern Caps Lock key.
- **F-Lock:** Toggles the behavior of the function keys (F1-F12) between their standard and secondary/multimedia key assignments.

### Functionality
- Toggle State: Lock keys operate as a latching switch. The state remains active until the lock key is pressed again.
- Indicator: Lock keys typically have an indicator light (LED) on the keyboard to show their active state.
- Universal Behavior: The toggle mechanism and resulting key behavior are standard across most PC-compatible keyboards.

```json
{
  "@context": "https://schema.org",
  "@type": "Thing",
  "name": "Lock key",
  "description": "A physical button on a computer keyboard that toggles the persistent state of an application or input feature, such as Num Lock or Caps Lock.",
  "url": "https://www.wikidata.org/wiki/Q758387",
  "sameAs": [
    "https://en.wikipedia.org/wiki/Lock_key",
    "https://www.wikidata.org/wiki/Q758387"
  ],
  "additionalType": "computer key"
}