Folafunmi Mustapha

In this blog post, we will dive into the basics of cache control headers and explore why they are essential for website performance. Cache control headers are a set of HTTP Cache headers that tell browsers how long to cache website content, such as images, videos, or HTML pages.

As websites continue to evolve and code complexity increases, it’s crucial to understand the role that cache control headers play in optimizing the user experience. But first, what is a cache?

Browsers use an HTTP cache to store resources associated with a particular request (such as images from a web page which it can then reuse on subsequent similar requests. 

This reusability possesses benefits of the request not having to reach the origin server but can the served already stored responses associated with a similar request. HTTP cache control headers provide browsers with information on how to handle caching concerning a particular request. In this blog post, we will dive into the basics of cache control headers and explore why they are essential for website performance.

Also, read: 11 Great Websites to Test Your Code Online

Table of Contents What are cache control headers? Why are cache control headers important? Types of cache control directives max-age Private Public No-cache no-store Use cases for cache control directives Conclusion FAQs

What are cache control headers?

Cache control headers are a set of HTTP Cache headers that tell browsers how long to cache website content, such as images, videos, or HTML pages. These headers control the browser’s cache and determine whether the content should be stored in the browser’s cache or whether it should be requested from the server each time a user visits the website.

Also, read: Top 21 HTML Interview Questions and Answers for 2023

These are set as ‘key-value’ pairs in the headers of a request or response, with the key being ‘cache control ’ and the value being the ‘cache directives’.

Why are cache control headers important?

Website cache control headers are essential for website performance because they help to reduce the amount of data that needs to be transferred between the server and the browser. When the browser caches website content, it reduces the time it takes to load the page, making the website faster and more responsive for users. This can also reduce the strain on the server, improving its overall performance.

Types of cache control directives

There are several types of cache control headers that website owners and developers should be familiar with. These include

max-age: This directive specifies the time-to-live(TTL) which is the maximum amount of time that content can be cached in the browser. For example, if the max-age header is set to 3600 seconds, the browser will cache the content for one hour before requesting it again from the server.

public: This directive indicates that the content can be cached by any cache, including browser caches, proxy caches, and CDN caches.

private: This directive indicates that the content is only intended for the user’s browser and should not be cached by other caches.

no-cache: This directive tells the browser that the content should not be cached, and it must be requested from the server each time the page is loaded.

no-store: This directive is similar to no-cache, but it also tells caches not to store the content on disk.

A full list of cache directives for requests and responses can be found here. 

Note that:

• Directives are case insensitive but it’s generally recommended to use lowercase as some implementations do not accept uppercase
• Multiple directives are comma-separated
• Some directives have optional arguments e.g max-age

Use cases for cache control directives 

Here are some examples of when to use different types of cache control directives:

max-age: This directive is useful when the content on your website doesn’t change frequently. For example, if you have an image on your website that rarely changes, you can set the max-age header to a high value, such as one week, so that the browser can cache the image for that period.

public: This directive is useful when you want to allow both the browser and any intermediate caches, such as proxy servers or CDN caches, to cache the content. This header is often used for static content, such as images, videos, and CSS files, that can be safely cached.

private: This directive is applicable when you have content that is specific to a single user and should not be cached by other caches. For example, if you have a user’s personal information or shopping cart contents, use the private header to ensure that this information is only stored in the user’s browser cache.

no-cache: This directive is useful when you want to ensure that the browser always requests fresh content from the server, even if it has been previously cached. For example, if you have a page on your website that displays real-time data, such as stock prices, you may want to use the no-cache header so that the latest data is always displayed.

no-store: This directive is useful when you want to ensure that no cache, including the browser cache, proxy cache, or CDN cache, stores the content on disk. This header is often used for sensitive information, such as login credentials or payment information, that should not be stored on any cache.

It’s worth noting that different types of cache control headers can be used together, and the choice of which headers to use will depend on the specific requirements of your website. The key is to understand the purpose of each header and how it affects the behavior of the browser cache, so you can make informed decisions about which headers to use.

Conclusion

cache control headers are a crucial aspect of website performance, and website owners and developers should understand their role in optimizing the user experience. 

By controlling the browser’s cache and determining how and when content is stored, cache control headers can reduce the amount of data that needs to be transferred between the server and the browser, improving website performance and responsiveness. Whether you’re a website owner or a developer, mastering cache control headers is an essential part of building and maintaining a fast and efficient website.

If you’re a developer looking for remote software jobs with top US companies, try Turing. Head over to the Apply for Jobs page to get started. 

FAQs

1. What is the difference between public cache control and private cache control directives?
   
   The public cache control directive specifies that a resource can be cached by any intermediate cache, while the private cache control directive specifies that a resource can only be cached by a specific user agent.
   
   
2. How can I set cache control headers in my web server or application?
   
   The specific method for setting cache control headers will depend on the web server or application being used. In general, you can set cache control headers in the server configuration or the code for your web application.
   
   
3. What is the difference between no-cache and no-store directives?
   
   The no-cache directive specifies that a resource must be revalidated by the user agent before it can be used from the cache, while the no-store directive specifies that a resource should not be stored in the cache at all.
   
   
4. How does the must-revalidate directive work?
   
   The must-revalidate directive specifies that a resource must be revalidated by the user agent before it can be used from the cache. This helps ensure that the user always sees the most recent version of the resource.
   
   
5. What is the purpose of the stale-while-revalidate directive?
   
   The stale-while-revalidate directive specifies that a cached resource can be served to the user while the cache is being updated with a new version of the resource. This can help to improve website performance by reducing the amount of time it takes to load the resource.
   
   
6. What is the difference between expires headers and cache control headers?
   
   Expires headers specify an absolute date and time at which a resource will expire and should be revalidated, while cache control headers provide more granular control over caching behavior and can be used to specify relative time intervals for caching.
   
   
7. What is the difference between max-age cache control and s-maxage cache control directives?
   
   The max-age cache control directive specifies the maximum amount of time that a resource can be cached by a user agent, while the s-maxage cache control directive specifies the maximum amount of time that a resource can be cached by an intermediary cache such as a proxy or CDN.
   
   
8. How do cache control headers impact caching by intermediaries such as proxies and CDNs?
   
   Cache control headers can impact caching by intermediaries such as proxies and CDNs by providing instructions on how the resource should be cached and for how long. This can help to ensure that users are always seeing the most up-to-date version of the resource, regardless of whether it is being served from a cache or directly from the origin server.

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Core Web Vitals are a set of user-focused metrics designed to measure a page’s “health” in terms of providing a smooth and seamless user experience.

Today, having a fast, smooth, and user-friendly website has become more important than ever. In order to enhance the experience of users on websites that it ranks, the search giant Google in May 2020 announced its Core Web Vitals, which are a group of user-focused metrics designed to measure a web page’s “health” when it comes to providing a smooth user experience.

These essentially stand as KPIs (Key Performance Indicators) for developers and a clear area of optimization for web technologies.

Also, read: The 9 Best KPIs for Your SaaS Platform

What are Core Web Vitals?

Core Web Vitals are a set of metrics that measure a website’s performance and user experience. These metrics are designed to help developers as well as non-tech-savvy folks understand how their site is performing from a user’s perspective and identify areas that need improvement. Therefore, expertise in performance isn’t needed to tell how well a site performs against another. A Core Web Vitals report can help you understand this.

Core Web Vitals are a subset of the Web Vitals and each targets a distinct facet of a user’s experience

The Core Web Vitals metrics include Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS). Let’s take a look at them one by one. 

1. Largest Contentful Paint (LCP)
   

   Largest Contentful Paint (LCP) is a metric that measures the loading speed of a page. It is calculated as the time it takes for the largest image or text block on a page to load and become visible to the user. A good LCP score is typically 2.5 seconds or less. A slow LCP can lead to a poor user experience, as users are likely to abandon a site that takes too long to load.

2. First Input Delay (FID)
   

   First Input Delay (FID) is a core web vitals metric that measures the responsiveness of a website. It is calculated as the time it takes for a website to respond to a user’s first interaction with the site, such as clicking a button or typing in a text box. A good FID score is typically 100 milliseconds or less. A slow FID can lead to a poor user experience, as users are likely to become frustrated with a site that takes too long to respond to their actions.

3. Cumulative Layout Shift (CLS)
   

   Cumulative Layout Shift (CLS) measures the visual stability of a website. It is calculated as the total amount of layout shifts that occur on a page due to changes in the layout, such as images or text blocks that move or resize while the page is loading. A good CLS score is typically 0.1 or less. A high CLS score can lead to a poor user experience, as users are likely to become frustrated with a site that changes unexpectedly or feels unresponsive.

Why are Core Web Vitals important?

Core Web Vitals are important for several reasons. Firstly, they help webmasters understand how their site is performing from a user’s perspective. By tracking and measuring the performance of their site, webmasters can identify areas that need improvement and make changes to create a better user experience.

Secondly, Core Web Vitals are a ranking factor for search engines like Google. Sites with poor Core Web Vitals scores are likely to rank lower in search results, making it more difficult for users to find them. On the other hand, sites with good Core Web Vitals scores are likely to rank higher, making it easier for users to find them.

Finally, Core Web Vitals are important because they directly relate to user experience. A site with poor Core Web Vitals scores is likely to have a poor user experience, leading to high bounce rates and low engagement. On the other hand, a site with good Core Web Vitals scores is likely to have a better user experience, leading to low bounce rates and high engagement.

How to improve Core Web Vitals?

There are several steps you can take to improve Core Web Vitals. Here are some of the most effective methods:

1. Optimize images and other media
   

   One of the most common causes of slow LCP scores is large, unoptimized images and other media. To improve your LCP score, you should optimize all images and other media on your site by reducing their file sizes and compressing them where possible. You can use tools such as Kraken.io or TinyPNG to automate this process.

2. Minimize JavaScript and CSS
   

   JavaScript and CSS are essential for many modern websites, but they can also slow down page load times if not optimized properly. To minimize the impact of these files on your Core Web Vitals scores, you should minimize their size and use techniques such as lazy loading and asynchronous loading to reduce the amount of code that needs to be processed on page load.
   
   Also, read: 11 Great Websites to Test Your Code Online

3. Improve server response times

   Another key factor in improving your Core Web Vitals scores is the speed of your server. If your server is slow to respond to requests, it can negatively impact your FID scores. To improve your server response times, you should ensure that your server is running on modern hardware, optimize your database queries, and use caching and other performance optimization techniques where possible.

4. Avoid intrusive ads and pop-ups

   Intrusive ads and pop-ups can also negatively impact your CLS scores by causing layout shifts on your pages. To avoid these issues, you should minimize the use of intrusive ads and pop-ups and ensure that any that are used are positioned and sized in a way that minimizes layout shifts.

5. Use tools to monitor and track your Core Web Vitals scores
   

   Finally, it’s essential to use tools to monitor and track your Core Web Vitals scores over time. This will help you identify areas where your site is underperforming and take action to improve your scores. Google provides a number of tools to help you monitor and track your Core Web Vitals scores, including the PageSpeed Insights tool and the Chrome User Experience Report.

In sum

Core Web Vitals are a set of metrics that are critical to the success of any modern website. By understanding what they are and how they impact user experience, you can take steps to improve your scores and create a better user experience for your visitors. Whether you’re a webmaster or a business owner, it’s essential to stay up-to-date on the latest developments in Core Web Vitals and take action to ensure that your site is performing at its best.

Are you a web developer looking for a high-paying remote job with flexible work timings? Try Turing! Top US companies are hiring web developers with Turing. Head over to the Apply for Jobs page to know more! 

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