Cache memory on a computer is essentially a storage container. Data that was recently used by the central processing unit (CPU) is stored within the cache memory, and the CPU can retrieve this data extremely fast and use it when processing the next batch of information. A great example of a common way in which cache is used is the many web addresses, images, and pages that your browser regularly gathers and stores in a folder on your computer’s hard drive.

What is Cache?

Pronounced “cash,” cache is a smaller but faster compartment of memory that provides support to the computer’s main memory. In other words, cache is designed to speed up the memory function. So, how does it work? When you pull up a webpage, your computer checks the cache to see if the information it needs to display the page is stored in there. If it is, it is known as a “cache hit.” If it is not, it is known as a “cache miss.” In the latter case, the computer sends a request in almost the same instant to the slower memory location in order to retrieve the requested data.

What Are the Cache Levels?

Even if your computer has main memory (RAM) with greater capacities and a faster microprocessor, a bottleneck can still occur when data moves between the CPU and RAM. Cache is a type of supplemental memory built for the purpose of more quickly conveying information between these two computer components. Over time, your computer builds a library of frequently used information, which is then stored into the cache. The purpose of “caching” is to accelerate your system’s speed and more quickly retrieve information. Not only does caching help reduce logjams at the RAM and CPU, but it also allows you to perform tasks faster because the data is more rapidly transmitted from the cache to the CPU.

There are three levels of cache. The first, level 1 (L1), consists of a high-speed cache that is integrated right into the processor. One of the more significant motivations behind L1 cache is the locality of reference. This essentially means that a website or page that was recently accessed by the CPU is more likely to be revisited in the short term. So, the L1 cache holds this recent data. When your computer needs the data again, it first checks the L1 cache. Since the data is held there, the microprocessor does not need to go back to the main memory, which is two times slower.

Secondary cache, or level 2 (L2), on a computer is typically located on a memory card that is near the processor. It is controlled by a circuit, known as the L2 controller, which is integrated into the motherboard, and L2 cache directly links to the central processing unit. The L2 cache is responsible for catching recently used data that was not stored in the L1 cache. On many personal computers, the L2 cache allows the process to obtain approximately 95 percent of the data it needs from the cache.

Level 3 (L3) cache is specialized memory that improves L1 and L2 cache performance. Although it can be drastically slower than L1 or L2, it is usually two times faster than RAM. Multicore processors may have an L1 and L2 cache dedicated to each processor, but they may share a common L3 cache.

Cache provides quicker data storage and faster access by holding data and information that is routinely and recently accessed by the processor. Thus, when a processor requests a website, page, or data that is stored in the cache memory, it does not need to go to the slower main memory in order to retrieve the information.