Browser Terms Explained: Referrer Policy

When we navigate the internet, we leave a trail of information behind us. This trail is known as the referrer, and it tells the website where we came from. Referrer Policy is a security feature that governs how much information websites can receive about us through this referrer trail. In this article, we'll look at what Referrer Policy is, why it's important, and how to implement it.

Understanding Referrer Policy

Before we dive into the details, let's look at what Referrer Policy is and why it matters. Essentially, Referrer Policy is a mechanism that controls the information sent to a website when we click a link. The referrer information includes details such as the website we came from, the search term we used to find the website, and even the individual page we were on before clicking the link.

This information can be useful for websites to understand how their users arrived at their page and to monitor their site's traffic. However, this information can also be used to track individual users, which can compromise their privacy.

It's important to note that not all websites use Referrer Policy, and some may not even be aware of it. This means that users could potentially be sending sensitive information to websites without their knowledge.

What is a Referrer Policy?

A Referrer Policy is a security feature that determines how much information is sent to a website from the referrer when we click on a link. The Referrer Policy dictates whether the referrer information will be sent in whole or in part, or not at all.

There are several types of Referrer Policy, including strict-origin-when-cross-origin, no-referrer-when-downgrade, and origin-when-cross-origin. Each type has its own level of security and privacy protection.

Strict-origin-when-cross-origin, for example, only sends the full referrer information when the destination website is on the same domain as the source website. This means that if you click a link from example.com to example.net, the full referrer information will be sent. However, if you click a link from example.com to google.com, only the origin (example.com) will be sent.

Importance of Referrer Policy in Web Browsing

Referrer Policy is an important security feature that protects user privacy while browsing the internet. Without Referrer Policy, websites could potentially gather a lot of personal information about their users, including search queries and browsing history.

Additionally, Referrer Policy can help prevent cross-site request forgery (CSRF) attacks. These attacks occur when a website is able to make a request to another website on behalf of the user, potentially allowing the attacker to access sensitive information or perform actions on the user's behalf. Referrer Policy can prevent these types of attacks by limiting the information that is sent from the referrer.

How Referrer Policy Affects User Privacy

With Referrer Policy, users have control over how much information they give to websites. By limiting the amount of information sent through the referrer, users can protect their privacy and prevent websites from tracking them.

However, it's important to note that Referrer Policy is not a foolproof solution. Websites can still track users through other means, such as cookies and fingerprinting. Additionally, some browsers may not fully support Referrer Policy, which could lead to inconsistent results.

Overall, Referrer Policy is an important tool in protecting user privacy and preventing malicious attacks. By understanding how it works and making informed decisions about which Referrer Policy to use, users can take control of their online privacy and protect themselves from potential threats.

Different Referrer Policy Values

When it comes to user privacy, Referrer Policy values play a crucial role. Let's take a closer look at the different Referrer Policy values and what they mean for user privacy.

No-Referrer

If the Referrer Policy is set to "no-referrer," no referrer information will be sent to the website at all. This is the most secure Referrer Policy value, as it completely hides user information from websites. This is particularly useful when browsing sensitive content or when sharing confidential information.

No-Referrer-When-Downgrade

If the Referrer Policy is set to "no-referrer-when-downgrade," referrer information will only be sent to an HTTPS website from an HTTPS website. If the link goes from an HTTPS website to an HTTP website, no referrer information will be sent. This Referrer Policy value is slightly less secure than "no-referrer," but still protects user information when moving from HTTPS to HTTP. This is useful when browsing websites that use both HTTP and HTTPS protocols.

Same-Origin

If the Referrer Policy is set to "same-origin," referrer information will only be sent to the same website's pages. In other words, if you click on a link to a different website, no referrer information will be sent. This Referrer Policy is a good balance between privacy and functionality. It allows users to navigate within a website without disclosing their browsing history to external websites.

Origin

If the Referrer Policy is set to "origin," referrer information will only be sent to the target website's domain, but not the full URL. For example, if you click on a link from "example.com" to "blog.example.com," the referrer will only include "example.com" and not "blog.example.com." This Referrer Policy value maintains some functionality while reducing the amount of user information shared with websites. It's useful when browsing websites that have multiple subdomains.

Strict-Origin

If the Referrer Policy is set to "strict-origin," referrer information will only be sent to the target website's domain, but not the URL. This Referrer Policy value further limits the amount of information shared with websites. It's useful when browsing websites that have multiple pages or sections, but want to limit the amount of information shared with external websites.

Origin-When-Cross-Origin

If the Referrer Policy is set to "origin-when-cross-origin," referrer information will only be sent to a different website if the target website is using HTTPS. If the target website uses HTTP, no referrer information will be sent. If the target website uses HTTPS, only the domain information will be sent. This Referrer Policy value maintains some level of cross-site functionality while still protecting user privacy. It's useful when browsing websites that use both HTTP and HTTPS protocols and want to maintain some level of cross-site functionality.

Strict-Origin-When-Cross-Origin

If the Referrer Policy is set to "strict-origin-when-cross-origin," referrer information will only be sent to a different website if the target website is using HTTPS and has the same domain as the source website. Otherwise, no referrer information will be sent. This is the most restrictive Referrer Policy value, but also the most secure. It's useful when browsing websites that require the highest level of security, such as financial institutions or government websites.

Unsafe-URL

If the Referrer Policy is set to "unsafe-url," referrer information will be sent in full, including all query parameters and sensitive information. This Referrer Policy value is the least secure and should generally be avoided. It's useful only when browsing websites that require full referrer information to function properly, but even then, it should be used with caution.

Implementing Referrer Policy

Now that we understand the different Referrer Policy values, let's take a look at how to implement Referrer Policy on a website.

Setting Referrer Policy in HTML

To set the Referrer Policy in HTML, use the following tag:

<meta name="referrer" content="value">

Replace "value" with one of the Referrer Policy values listed above, such as "no-referrer" or "same-origin."

Setting Referrer Policy in HTTP Headers

You can also set the Referrer Policy in HTTP headers. To do so, use the following header:

Referrer-Policy: value

Again, replace "value" with one of the Referrer Policy values listed above.

Referrer Policy and Content Security Policy

You can also use Referrer Policy in conjunction with Content Security Policy (CSP) to further protect user privacy. By setting a strict Referrer Policy and a strict CSP, you can prevent websites from loading external resources and tracking user behavior.

Conclusion

Referrer Policy is an important security feature that protects user privacy while browsing the internet. By understanding the different Referrer Policy values and implementing them on websites, we can ensure that user information remains private and secure.

So next time you're browsing the web, keep an eye out for Referrer Policy and make sure your information is protected.