What is Caching and How does it Work?

What is Caching and How Does it Work 1

Over the last few years, e-commerce has seen such a huge boost that in the future physical stores will be minimal. Everyone wants to buy stuff over the internet. As the internet users have grown exponentially, so has the traffic on the internet. An increase in traffic means an increase in data transfer.

This high volume of data exchange over the internet has given a headache for e-commerce sites or just any application. Any delay in loading a page or slow performance will surely affect the rating of your website, and the visitors will get disappointed. Such delays will likely make the visitors leave your website and not return.

Hence avoiding downtime and reducing the data retrieval time is of utmost importance. This is how caching comes into the picture. Caching cannot be ignored anymore by any developer.

When you are new in the computing world, you will always come across terms such as DNS, cache, RAM, etc.  So let us start digging into the word Caching. We will discuss the meaning of caching, how the caching process works, why is caching important and also some of the risks associated with it. Also, we will discuss in detail the different types of caching.

What is Cache?

A cache is a component [hardware or software] that stores data. This data, when requested later, can be processed quickly. The data which is stored in the cache can be a copy of the data stored elsewhere. It can also be an earlier computation of the data.

Cache hit: This occurs when one finds the requested data in the cache.

Cache miss: This occurs when one cannot find the requested data in the cache.

Cache hits are achieved by reading the data from a cache. Data reading on the cache is faster than reading data from a data store. Hence the higher number of requests or cache hits are provided by the cache; then we can say that the system is performing at a faster rate.

Some pointers to be considered:

  • A cache is a special storage location for interim files, which makes any device or app run faster and efficiently.
  • When you open an app or a website for the very first time, a cache will store images, files and data on the device which you are using.
  • Now, this data that is cached will be used to quickly load the website or the app the next time you access it.

What is Caching?

Caching is the process that involves storing multiple data copies or files in an interim storage location which is known as a cache, so that these copies of data and files can be accessed later at a faster rate. It is the temporary storing of data for applications, browsers and servers, which makes sure that the user does not have the need to download these files every time they open an app or website. Cached data usually includes images, videos, audios, files, scripts etc.

Caching Working Principle

The data that is cached is usually stored in hardware like Random Access Memory [RAM], and it can be used with a related software application. There are a few layers in which the data is stored; it has a primary level and two secondary levels. This data has a time to live [TTL], which shows how long it should be cached, expires or the memory gets filled and so on. The main purpose of a cache is to improve the data retrieval capacity.    

Why is Caching Important?

Caching helps in increasing the performance of any application or website. Hence caching is crucial for developers. Users or developers do not want their applications to take a lot of time to load and for processing requests. Any developer would want their application to be the fastest version of that app.

And all the internet users won’t wait for more than a few seconds if the page is not loading. It is quite understood that no one wants to waste their time staring at the page loading window. High performance has become a critical aspect in the modern computing world. It cannot be avoided anymore. Caching is now used by most service applications making it omnipresent.

So when any application wants to compete in the internet market, then properly implementing the caching systems is very important.  Users do not want an explanation for the delay in opening or loading the web pages.   

Another crucial point of caching system is that it avoids creating new requests and re-generates the data every time. It allows us to avoid this redundant cycle.  Thus it reduces network overhead and also the overall usage of the Central Processing Unit (CPU). If the requests are complex in nature, then the load on the CPU might be high and caching help in reducing this substantially. This directly helps in prolonging the machine/server life. Caching system can also reduce the cost of the total infrastructure since it avoids creating new requests.

Different Types of Caching

Although caching sounds like a general term, there are different types of caching. Basically, there are key concepts to different approaches of caching. Let us take a look at them:

In-memory Caching

In this method, the data that is cached is directly stored in the RAM since it is faster than retrieving data from the hard drive. A common example of this type of caching would be the key-based database. It is like using key-value pairs of data wherein key could be some unique value and the value represented by cached data.   

In simple words, this means that every data file has a unique value that represents it. By requesting the value, the key-value database will find and retrieve the value associated with it. This type of caching is quite fast, efficient and easily understandable. This makes it the preferred caching approach for developers.

Database Caching

Most of the databases have some caching level of their own. These databases have an internal cache which is generally used for avoiding excess queries to the database. It caches the outcome of the previous queries which were executed. This way, the previously cached data is retrieved immediately. But this data that is cached is valid for a limited amount of time, so within this time, the database can stop executing repeated queries.

There are many ways to implement this approach; the most common way is by using key-value pairs. As explained above, the key serves as a marker to identify and locate the value. Object Relational Mapping [ORM] generally provides such a type of caching.

Web Caching

As the name suggests, this type of caching includes web data such as files, images, videos etc. Web caching is further divided into two subcategories:

Web Client Caching

Most internet users are familiar with this type of cache, and it is stored on the client’s devices which can be mobiles, laptops, computers etc. Also known as Web Browser Caching since it’s a part of browsers. It works as an endless cycle.

Whenever a user opens a website on the browser for the first time, the browser will store the data such as images, font styles, text, videos, audios etc. if the user opens the same page again, then the browser will look for its cache memory and will retrieve all the data which was previously cached. Since this data is stored on the user’s device, the browser is quick in retrieving the same. This is much faster than downloading the data again from the internet.  

Web Server Caching

As the name suggests, this type of caching approach involves storing the data resources on the web server for reusing. Usually, this approach is beneficial when there is a lot of content that is generated dynamically as it takes a lot of time for its generation. Similarly, this approach won’t work out when there is static content.

This method prevents the web servers from overload requests, thereby reducing the work and overall improving the request processing speed.

CDN Caching

Content Delivery Network [CDN] caches the web content such as audio/video files, web pages, scripts in a proxy server. It works as a gateway system between a user and the server, which stores the resources. When there is a request from a user for any resource, the proxy server will intercept the request and will try to find a cached copy of it. If the requested cached data is found, then it is immediately sent.

However, if the data is not found, then the request is sent to the main/origin server.  There is a large network of these proxy servers, and they are located worldwide. The user requests are sent to the nearest available server. Proxy servers are closer to the users than the origin server. This reduces the request load on the origin server.

How to Clear your Cached Data from Different Web Browsers and Devices?

Where have you heard about clearing cached data? It is probably when you are freeing up space on your mobile or computer. Suppose your mobile is taking a long time to process files etc., you tend to check the storage status. Cached files/data usually consumes a lot of space on your device. Hence clearing it once in a while is beneficial.

Clearing your cached data can be done in different ways. It usually depends upon the type of device being used. Following is the detailed process to be followed for clearing your cached data on computer devices. Let us look at the below processes for different web browsers:

Google Chrome:

The most common and widely used web browser all over the world. Let us look at the following steps:

  • Open Chrome. Click on the ‘Settings’ icon shown by three dots on the top right corner of the browser.
  • Then you have to select the ‘More tools’, then ‘Clear browsing data’.
  • Next, you have to click on the checkboxes for images, files, plugin data and cookies. Also, here you get the option to choose the time frame of data to be deleted. It could be from the previous day to ‘from the beginning’.
  • Next is to click on ‘Clear browsing data’. Now this entire process is for Chrome users on computers, iOS and Android devices.

Apple Safari:

The process should follow the below steps:

  • Open Safari browser. Then select the ‘History’ option, next ‘Clear history’ to delete the whole data that is stored in the browser.
  • Then it will have a drop-down menu that lets you select the time frame of data to be deleted. 
  • It ranges from last day, last two days or even the complete history. If you select the complete delete option, then it will delete all the browsing history, all the cookies and the entire cache from the browser.
  • Users can also select the specific sites that they want to clear the history. You just need to right-click and then delete them as per your choice.

Internet Explorer:

Well, this is not the most used web browser as of now but let’s take a look at the process:

  • Open Explorer and then select ‘Tools’ and then select ’Safety’.
  • Next, click on ‘Delete browsing history’. Click on all the relevant boxes which you want to clear or delete. These include cookies, temporary files etc.
  • The final step is to select ‘delete’. There is also a shortcut to open the entire browsing history, which is holding the Ctrl, Shift & Delete keys altogether.
  • Mozilla Firefox: Another popular browser used by everyone.
  • Open Firefox. Click on the ‘Library’ option. Next is to click on ‘History’ and then ‘Clear recent history’.
  • Select the time frame for the data to be cleared. Then there will be an arrow next to ‘Details’, which lets you select the type of information you need to clear.
  • The final step is to select ‘Clear now’, which will delete the cache.

Now the same applies to mobile devices. Data from the apps take a lot of the storage space. Cached data which is stored by the various apps on your phone can also be deleted by following the below process:

For Apple iOS device:

Let us take a look at it step by step.

  • The first step is to open the ‘Settings’ option.  Then go for the ‘General’ option.
  • Next, go to ‘Storage and iCloud usage’, then ‘Storage’ and ‘Manage storage’.
  • Select the app that you want from that list and click on it; go to ‘Documents and data’. If that app is using 500 MB or more space, then you need to reinstall the app to clear up space.

For Android devices: 

Open the ‘Settings’ menu. Then open ‘Apps’.

  • Select the app from which you want to clear cached data to free up space.
  • The amount of data stored by the app is displayed. You get the option to clear the data to free up space.

Positives / Advantages of Cache

There are three major benefits of cache; let us take a look:

  • Everything runs faster with the cache. The most important benefit of using cache is that it improves the overall performance of your system. A prime example would be, cache stores temporary copies [local files] of the website data; when you open a website for the first time, it will download all the resources. On your next visit, the data will be retrieved from these local files, hence saving your precious time.
  • The cache saves a lot of data. For increasing their performance, many apps store the most commonly and recently used data in their cache. This allows the apps to work faster, as mentioned in the above point, but it also does allow the ‘offline’ working of the apps. So when you don’t have any internet access on your phone, the app will use the cached data and continue working without an internet connection.
  • Cache stores data for later use. The efficiency of your overall system improves when you are downloading the files just once. If a local copy of the data is saved in the cache, then the app has no need to use battery power, time and other things for downloading the data for a second time. Instead, only the edited or new files are to be downloaded.

Negatives / disadvantages of Cache

Let us discuss some of the disadvantages of cache.

  • Cache eats up bulk of the storage capacity. A cache is just a temporary data file, but over time it can grow exponentially and take much of the free space of your device. Deleting the cache can free up a lot of space.
  • The corrupt cache can damage the working of an app. If there is an error in the cached data, then the app can malfunction or worst, it can crash.

You can also check our article on What is Cloud Hosting and How does it Work?

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