# cache

> computing component that transparently stores data so that future requests for that data can be served faster

**Wikidata**: [Q165596](https://www.wikidata.org/wiki/Q165596)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Cache_(computing))  
**Source**: https://4ort.xyz/entity/cache

## Summary  
Cache is a computing component that transparently stores data so that future requests for that data can be served faster. By keeping frequently accessed information close to the processor or application, cache reduces access latency and improves overall computer performance.

## Key Facts  
- Cache is classified as a **recording medium** and **computer hardware** (subclass_of).  
- Its primary purpose is to enhance **computer performance** by reducing data‑access time.  
- Types of cache include **CPU cache**, **disk cache**, **web cache**, **ARP cache**, and **negative cache**.  
- CPU cache is a **dynamically managed local memory** that mirrors main memory to lower access cost (34 sitelinks).  
- The Wikipedia article for this concept is titled **“Cache (computing)”** and described as “computing component that transparently stores data so that future requests for that data can be served faster.”  
- The entity has the following identifiers: **GND ID 4362843‑6**, **YSO ID 28584**, **Freebase ID /m/01zyw**, **KBpedia ID CacheComputing**, **WordNet ID 02938401‑n**.  
- An illustrative image is available at **https://commons.wikimedia.org/wiki/Special:FilePath/External_Cache_486x.jpg** (physical chips used as CPU cache).  
- Alias terms include **computer cache, data cache, memoria caché, Prefetching, mise en cache**, among others.  
- Related technologies: **Translation Lookaside Buffer (TLB)**, **Memcached**, and **ReadyBoost**.  
- The Intel Core i7‑4770HQ CPU contains cache memory as part of its architecture.

## FAQs  
### Q: What is a cache in computing?  
A: A cache is a hardware or software component that temporarily stores copies of data so that future requests for that data can be served more quickly, reducing latency and improving performance.  

### Q: How does cache improve computer performance?  
A: By keeping frequently accessed data close to the processor or application, cache eliminates the need to fetch the same information repeatedly from slower storage layers, thereby speeding up data retrieval and overall system responsiveness.  

### Q: What are the main types of cache?  
A: The most common types are **CPU cache** (L1, L2, L3), **disk cache**, **web cache**, **ARP cache**, and **negative cache**, each serving a specific layer of the computing stack.  

### Q: Is cache the same as RAM?  
A: No. Cache is a smaller, faster memory tier that sits between the processor and main memory (RAM). It stores only a subset of data that the processor is likely to reuse, whereas RAM holds the full working set of active data.  

### Q: Can software use cache?  
A: Yes. Software solutions such as **Memcached** and **ReadyBoost** implement caching in memory or on disk to accelerate application‑level data access.

## Why It Matters  
Cache solves the fundamental bottleneck of latency in modern computing systems. As processors have become orders of magnitude faster than main memory and storage devices, the time required to fetch data from these slower layers can dominate overall execution time. Cache bridges this speed gap by providing a high‑speed storage tier that anticipates and retains data likely to be needed again soon. In CPUs, multi‑level caches (L1, L2, L3) dramatically cut instruction and data fetch times, enabling higher instruction‑per‑cycle rates and smoother multitasking. In web and network contexts, caches reduce bandwidth consumption and server load by serving repeated requests locally. Disk and software caches similarly accelerate file I/O and application performance. Without cache, everyday tasks such as loading web pages, launching programs, or running complex simulations would be perceptibly slower, limiting both user experience and the feasibility of high‑performance computing workloads.

## Notable For  
- **Transparency:** Cache operates without requiring explicit instructions from applications; it works automatically behind the scenes.  
- **Multi‑Level Architecture:** Modern CPUs employ hierarchical caches (L1, L2, shared L3) to balance speed, size, and power consumption.  
- **Broad Applicability:** The caching concept spans hardware (CPU, disk) and software (web, ARP, negative caches), making it a universal performance‑enhancement technique.  
- **Negative Caching:** Stores information about failed or missing responses, preventing repeated futile requests.  
- **Integration in Major Processors:** Intel’s Core i7‑4770HQ, among many others, incorporates dedicated cache memory as a core architectural feature.

## Body  

### Definition  
Cache is a computing component that **transparently stores data** so that subsequent requests for the same data can be served faster. It acts as an intermediate storage layer between fast processors and slower memory or storage subsystems.

### Types of Cache  

- **CPU Cache** – Local memory within a microprocessor that mirrors portions of main memory. It is dynamically managed and exists in multiple levels (L1, L2, L3).  
- **Disk Cache** – Stores data that resides permanently on a hard drive or SSD, reducing read/write latency.  
- **Web Cache** – Temporarily holds web documents (HTML, images, etc.) to speed up page loads for repeated accesses.  
- **ARP Cache** – Keeps recent Address Resolution Protocol mappings to avoid repeated network lookups.  
- **Negative Cache** – Remembers failed or missing responses, preventing repeated attempts for unavailable resources.  

### Architecture and Levels  

- **L1 Cache** – Smallest and fastest, located directly on the processor core.  
- **L2 Cache** – Larger, may be private to a core or **shared L2 cache** among several cores.  
- **L3 Cache** – Even larger, typically shared across all cores on a die.  

These levels form a hierarchy where data moves from slower to faster storage as it becomes more frequently accessed.

### Implementation  

- **Hardware Cache** – Built into CPUs, memory controllers, or dedicated chips (e.g., external cache chips shown in the image).  
- **Software Cache** – Implemented by applications or services (e.g., Memcached, ReadyBoost) using system RAM or disk space.  

### Performance Impact  

- Reduces average memory access time from hundreds of nanoseconds (DRAM) to a few nanoseconds (L1 cache).  
- Lowers bandwidth consumption on networks and storage buses.  
- Improves throughput for both single‑threaded and multi‑threaded workloads.  

### Related Technologies  

- **Translation Lookaside Buffer (TLB)** – A specialized cache for virtual‑to‑physical address translations.  
- **Memcached** – An in‑memory key‑value store used to cache database query results, API calls, and page fragments.  
- **ReadyBoost** – A Windows feature that uses USB flash drives as a supplemental disk cache.  

## Schema Markup  
```json
{
  "@context": "https://schema.org",
  "@type": "Thing",
  "name": "Cache (computing)",
  "description": "Computing component that transparently stores data so that future requests for that data can be served faster.",
  "sameAs": [
    "https://en.wikipedia.org/wiki/Cache_(computing)",
    "https://www.wikidata.org/wiki/Q"
  ],
  "additionalType": "ComputerHardware"
}

## References

1. Integrated Authority File
2. Freebase Data Dumps. 2013
3. YSO-Wikidata mapping project
4. National Library of Israel
5. KBpedia
6. GF WordNet
7. [OpenAlex](https://docs.openalex.org/download-snapshot/snapshot-data-format)