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What is a Cache? 6 Types You Need to Know
By Tibor Moes / January 2023
Just clear your cache and everything will be as right as rain. How many times have you received that advice when troubleshooting an issue?
We bet it’s a lot because clearing the cache is one of the most common solutions to a bunch of tech problems. The thing is, you may not know what a cache is, how to access it, or why clearing it can fix your computer issues. That’s where this article comes in.
We’re going to explore the different types of cache so you know what you’re looking for the next time you need to take action.
Summary: A cache is a storage location reserved for specific types of files that help websites, software, and browsers run faster. They’re where your computer keeps temporary files that make it easier for the device to retrieve key information. There are several cache types, including primary, secondary, and main caches in your computer’s memory. You may also have to deal with data or web caches.
Tip: The online space can be a complicated and dangerous place. Protect your devices with antivirus software and safeguard your online privacy with a VPN.
What is a Cache?
Cache is a form of auxiliary memory that holds data and instructions that an app or website needs regular access to. It’s fast, easy to access, and allows whatever application or website that uses the files in the cache to work faster.
Your cache takes up space on your device’s hard drive. As you access more websites and install more apps, the amount of memory your cache needs increases. If you don’t clear your cache, you’ll find that your hard drive starts filling up faster and the device itself may slow down.
So, you can think of cache as your computer’s memory bank.
It contains a bunch of information and data that apps and websites find useful. But if you aren’t careful, your memory bank gets bogged down as you try to put too much stuff into it.
The Cache Types
There are several cache types, each of which serves different purposes. Your device has its own cache, which is divided into several levels. This CPU cache exists to retrieve frequently used information for your device. Other caches relate to web browsers and apps, with each leveraging different types of cache.
Cache Type No. 1 – Memory Cache
We can divide cache memory into three categories:
- Primary Cache L1
- Secondary Cache L2
- Main Memory L3 Cache
Some of these caches work directly with your device’s central processing unit (CPU). Others are external caches that store data away from the CPU but allow for easy access when needed. But all focus on caching data that your device requires to run quickly and correctly.
Primary Cache L1
This cache type is part of the processor in your device’s central processing unit. It tends to be extremely small, with its memory ranging between 2 and 64 kilobytes. As such, your device’s primary cache isn’t designed to hold a lot of data.
Instead, it works a lot like random access memory.
Instructions get stored in the primary cache for your device to access when it needs them. When the instructions aren’t useful anymore, they get deleted to make way for new instructions. The key benefit of a primary cache is that it works at almost the same speed as your processor.
Secondary Cache L2
Secondary caches are the middlemen between your device’s processor and the device’s main memory. If a cache miss occurs, your device usually jumps down to the secondary cache to see if it can find what it’s looking for. A cache miss refers to any failed attempt to pull an instruction out of a cache. In this case, an instruction may not get loaded into your device’s primary cache quickly enough, leading to the device searching the secondary cache instead.
This cache type is larger than the primary cache. It tends to range from 256 to 512 kilobytes. It’s also held externally to the processor, meaning it needs to be connected using a high-speed bus.
Main Memory L3 Cache
Main memory cache is a bit misleading here because this cache tends to be faster than your device’s main memory. However, it’s stored away from the CPU, which is why it’s named that way.
This is the largest of the three CPU-related caches. L3 cache tends to clock in at between 1 and 8 megabytes, meaning it can hold a lot more instructions. If you have a multicore processor, you’ll usually find that your L3 cache serves all of the cores at the same time.
Cache Type No. 2 – Web Cache
Have you ever wondered why a web page that you visit often tends to load faster than a page you’ve never visited before?
You can thank web caches for that.
Web caches store data from browsers, websites, and servers that allow them to quickly access information needed to speed up loading times. Without web caching, your browser has to send a new request every single time you access a web page.
If the information is already in a device’s cache, a website can deliver static content quickly. Delays only occur when the user accesses something they haven’t seen before.
The idea behind the various types of web caches is that they limit the number of server requests your browser makes. Fewer server requests lead to faster loading times, in addition to reducing the load placed on the server behind a website. Webmasters save money on network costs because of this reduced load.
There are four main types of web cache:
1. Site Cache
2. Browser Cache
3. Micro Cache
4. Server Cache
Also known as page cache, site cache stores data about a website the first time you visit it. If you return to the website, it pulls the saved data from the site cache to allow certain elements to load faster. For example, the files stored in a site cache allow the page to display static web content faster than it would with a fresh request.
Website owners can determine how much time a file stays in the site cache.
If elements of the website are likely to stay static for years, the owner may set a file’s expiry date several years into the future. But files related to dynamic elements of a website tend to have much shorter expiry dates. These shorter dates act like triggers to tell the website when it needs to refresh the files stored in your device’s site cache.
As a result, site caches are best used for websites that have a lot of static content. The more dynamic the website is, the less of a use it has for site cache.
As a side-note, you have control over the site cache. Though the website owner may set an expiry date for their cached files, you can choose to clear this cache at any time. The only downside to this is that it’ll take a few extra seconds to load web pages you’ve visited before. Still, it’s a good choice to make if your device’s site cache becomes so large that the stored data starts eating away at your hard drive.
The browser cache is a type of site cache that’s built into your web browser. Much like a site cache, it stores a cached version of most of the websites you visit. This enables the browser to load websites faster, providing you with a better web surfing experience.
Browser caches work by storing elements of a website, such as HTML pages, multimedia content and images, and CSS stylesheets. It then groups those elements with other files related to the website’s content to create a faster browsing experience. Cached images and content load faster because your browser doesn’t have to download them again to display them.
Your entire browsing history is stored in the browser cache, which means you can clear browsing data by deleting your browser cache. That’s another key feature of this type of cache. It’s controlled by the user, meaning you always have the option of clearing it if it starts to take up too much storage space.
As with a site cache, website owners can set expiry dates on the cached version of files stored in the browser cache. This allows the site to serve you with updated files for dynamic elements while ensuring you keep the same files for static content.
A lot of website owners and web users aren’t aware of this type of cache memory. The micro cache stores content for short periods to ensure they display correctly. For example, it’s commonly used to store the static elements of a dynamic piece of content. The micro cache stores files for up to 10 seconds.
This short storage time means this is the least common type of web cache. There aren’t many websites that benefit from using it. Those that do usually feature rapidly changing content with static elements.
A good example is a stock website. The numbers change constantly but the graphs and table diagrams remain static. Those static elements are stored and refreshed in the micro cache every 10 seconds, with the more dynamic elements changing as and when they need to.
You’re able to clear this type of cache memory. However, its extremely limited use means that doing so won’t free up much storage space.
Server cache is a general term that covers several types of cache memory. These include object caching, opcode caching, and content delivery network (CDN) caching. This is the only form of web caching that you don’t control. Instead, it applies to the website owner because server caches store frequently accessed data on the website’s server.
Website owners use the server cache to reduce server loads.
Content stored in a server cache can be returned to a browser as soon as it’s requested. This faster delivery allows the website to handle more traffic while delivering the content faster. The website will retrieve data from the cache rather than having to spend time navigating the website via the server to locate its standard memory location.
Think of the server cache as a method of storing data that a website owner knows that visitors will need regularly. The site checks this form of temporary storage for requested data first before it searches the rest of the server.
Cache Type No. 3 – Application/Software Caches
Most apps maintain their own caches to save files and data that the developer thinks users need quick access to. These caches allow the app to pull frequently accessed data from the cache memory to serve it up to users.
Data stored in software caches vary depending on the application. Some store your search history or user preferences. Others may store video thumbnails or background images. Whatever the stored content may be, all software caches aim to reduce latency and provide a cost-effective way for users to access frequently accessed content.
Cache Type No. 4 – Data Caching
If a webpage or application needs to retrieve data from a database, it likely used data caching. That’s because the input and output requests needed to pull data from databases are hardware-intensive. If users request the same set of data often, and that data doesn’t change over time, it’s likely the developer will use data caching to serve it up more quickly.
The data cache is maintained on the web or application server. Storing data in these caches lowers the demand placed on servers, making the use of data caches a more cost-effective way to deliver data.
You likely won’t have control of the files stored in this type of cache memory.
Instead, the developer needs to create a way for themselves to clear the cache if the data it holds goes out of date or becomes obsolete.
Cache Type No. 5 – Application/Output Caches
We spoke earlier about caches related to content delivery networks.
This is the type of cache those networks often used. Application and output caching are built into many contentment management software packages. As with most other cache types on this list, they reduce server overhead by storing static content that a user accesses regularly. If a page contains mostly written content, this cache improves application performance by allowing the page to load faster.
Application and output caches operate at the server level.
They cache raw HTML in cache memory, which allows for the faster loading of static pages. Smart uses of this type of cache can reduce webpage loading times by up to 50%.
Cache Type No. 6 – Distributed Caching
This type of cache memory is for the big boys. The likes of Google and Amazon use distributed caching because they have high-volume systems. This cache allows major companies to store data across several distributed database servers. The data in each of these database servers is cached in different web servers.
Those web servers supply data to applications within the distributed cache.
The key difference between distributed caching and other cache types is that this type of cache never runs out of storage space. If a storage limit is about to be reached, the company can simply add new servers to its pool without disrupting the user experience. As such, distributed caching is a great way for high-volume systems to account for increasing numbers of user visits.
Even though this is a form of specialized cache reserved for high data loads, it still serves the same function as most other cache types. Distributed caching allows cached data to be displayed quickly.
Cached Data Has Positives And Negatives
Though there are several cache types, they generally all serve the same purpose – loading cached data faster. If users access the same data types regularly, developers can use cache memory to serve that data to them faster. The result is webpages and applications that can access data in a matter of seconds, leading to a better experience for the user.
The issue is that the benefits of cached data relate solely to the website or application using the cache.
As a cache fills up, it takes up storage space that you might want to use for something else. Different caches can also affect your device. For example, mobile devices may run slower than they normally would as their various cache folders fill up.
So, the caching process has positives and negatives.
While it enables faster access to data, it can also slow down operating systems and use extensive amounts of storage space. Thankfully, you have control of most cache types. Clearing cache is often a simple case of navigating through a browser or applications settings menu to find the option to get rid of the stored files.
Ultimately, that choice depends on what you need from your device.
If you want faster application and website loading times, keeping files in cache is a good idea. But if you want to free up storage space and optimize how the device itself runs, regular cache clearing is recommended.
Frequently Asked Questions
What does it mean to Clear Cache?
Clearing the cache means deleting the files that are automatically stored in the cache when you visit a website or open a new app. Clearing often allows you to free up space, which is particularly useful for devices that have small hard drives. You may also speed up your device by clearing its cache.
Is it OK to Clear the Cache?
Yes, it is ok. Clearing your cache has several benefits for device performance and speed. It also protects personal information stored in the files inside your cache by preventing people from accessing them. Plus, clearing your cache prevents your device from trying to use old data when you fill out forms.
What are the benefits of Caches?
Caches have several benefits relevant to the software or website that place files into them. They can store key data, making it easier to fill out forms. Files in your cache also speed up the software or website they’re related to.
Author: Tibor Moes
Founder & Chief Editor at SoftwareLab
Tibor is a Dutch engineer and entrepreneur. He has tested security software since 2014.
Over the years, he has tested most of the best antivirus software for Windows, Mac, Android, and iOS, as well as many VPN providers.
He uses Norton to protect his devices, CyberGhost for his privacy, and Dashlane for his passwords.
This website is hosted on a Digital Ocean server via Cloudways and is built with DIVI on WordPress.
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