When you access a website, the browser uses many kinds of information to display the page.
Browser type. OS. Screen size. Language. Time zone. Supported fonts. Extensions. Canvas and WebGL rendering results.
Each of these is a small piece of information when viewed one by one. But when combined, they become characteristics of that browser environment.
The idea of using these characteristics to distinguish users is browser fingerprinting.
This article explains how browser fingerprinting relates to anonymity.
What Is Fingerprinting?
Browser fingerprinting is a method of combining browser and device characteristics to infer whether access is coming from the same environment.
It is somewhat different from methods where a website stores an identifier in the browser, such as a cookie.
s are used for identification when stored values are sent again. By contrast, fingerprinting uses the browser's visible appearance itself as material.
Item
Cookie
Fingerprint
Main material
Value stored in the browser
Browser and device characteristics
How it appears to the user
Easier to think about deleting or blocking
Hard to tell what is being used as material
How easily it changes
Changes when cookies are deleted
Tends to remain if settings and environment are the same
Impact on anonymity
Links repeat visits from the same browser
Shows signs of the same environment even without cookies
In other words, simply deleting cookies is not enough. If you keep using the same browser environment, other clues remain.
What Kinds of Information Become Material?
Fingerprinting material is information the browser uses to display pages or run features.
Information
What it shows
Anonymity caution
User-Agent
Browser, OS, version, and similar details
Becomes a broad characteristic of the usage environment
Screen size
Display area and device type
Becomes material suggesting the same device
Language settings
Preferred language
Becomes a clue to region or usage environment
Time zone
Device time setting
Connects to where and when you are active
Fonts
Available fonts
Becomes a characteristic of the OS or installation environment
Canvas
Browser rendering result
Becomes material for device, GPU, and browser differences
WebGL
Information around 3D rendering
GPU and driver characteristics appear
Extensions
Added features
Unusual combinations stand out
Not every website collects these in the same way. However, on pages where JavaScript is enabled, a lot of information from the browser side can be obtained.
When thinking about anonymity, you need to look not only at "information you entered," but also at "information the browser automatically exposes."
Why It Relates To Anonymity
For anonymity, the problem is that actions by the same person become linked.
For example, suppose you view a site from your home connection, then access the same site using a . The IP address has changed. Suppose you also deleted cookies.
Even then, if the browser characteristics are almost the same, signals that the access came from the same environment remain.
Fingerprinting alone cannot necessarily identify an individual. However, when combined with IP address, cookies, login state, access time, and post content, it becomes material for correlation.
What is dangerous for anonymity is not only one piece of information. It is the accumulation of small pieces of information.
Custom Settings Can Stand Out
When trying to increase anonymity, it can be tempting to customize the browser in detail.
Ad blocking. Anti-tracking settings. Special font settings. Many extensions. Fine-grained JavaScript controls.
These can be useful. However, when the combination of settings becomes unusual, it stands out instead.
For anonymity, "adding settings that look strong" is not always the right answer. In some situations, it is important to align with how many other users appear.
Browser follows this approach. Instead of adding conspicuous settings for each user, it creates an environment that looks as similar as possible, making identification by fingerprinting harder.
In other words, for anonymity, "joining a group that does not stand out" can matter more than "adding many defenses."
Uncommon combinations of extensions, special fonts, custom screen sizes, and overly detailed blocking settings become characteristics of the person. Settings meant to avoid tracking can instead become material for identification.
Differences Between Tor Browser and Regular Browsers
Regular browsers emphasize convenience and compatibility. For that reason, differences between users tend to be visible to sites.
Tor Browser is a browser that emphasizes anonymity. It not only uses the Tor network, but is also designed to align how the browser appears.
If you install everyday extensions in Tor Browser, fix the screen size in a custom way, or log in to a real-name account, anonymity weakens.
What to check in the browser environment
When thinking about browser fingerprinting, check the following points.
Are you reusing the same browser for anonymous use and real-name use?
Have you installed the same extensions?
Have you changed browser settings too much in a custom way?
Do screen size or language settings overlap with real-name use?
Are they remaining together with cookies or login state?
If you use Tor Browser, have you kept the standard settings?
What matters here is not looking only at fingerprints. Browser characteristics are correlated together with cookies, IP address, time, accounts, and post content.
Fingerprint defenses do not stand alone.
When using a designed environment such as Tor Browser, the basic rule is not to disrupt the standard settings substantially. When using a regular browser, the starting points are not mixing real-name use and anonymous use, not adding unnecessary extensions, and checking login state.
Sites Where You Can Check How You Appear
Browser fingerprinting can feel abstract when understood only through text. When you actually look at test sites, it becomes easier to understand what information about the browser environment is visible to websites.
EFF Cover Your Tracks is an EFF test site that lets you access an external site and check how identifiable your browser is to trackers and fingerprints. During the test, browser information is sent to EFF, so think carefully about when to use it in high-risk environments or real anonymous-use environments. The result is not a judgment of whether you are "completely safe," but it can be an entry point for understanding that browser information becomes identifying material.
BrowserLeaks Canvas is a test page where you can check part of the browser environment visible to websites, centered on Canvas. Because you can see individual values, it can help you learn how extensions and setting changes alter the way your browser appears.
These sites are learning-oriented check destinations. Use them not to feel reassured after seeing a result once, but to understand that "my browser is exposing more information than I expected."
Summary
Browser fingerprinting is the idea of combining browser and device characteristics to infer whether access is coming from the same environment.
User-Agent, screen size, language, time zone, fonts, Canvas, WebGL, extensions, and similar details become material.
Even if you delete cookies, if the browser environment is the same, signs that it is the same user remain. Even if you change the IP address, if the browser characteristics do not change, they become material for correlation.
For anonymity, adding custom settings is not always the right answer. In some situations, it is important to align with how many other users appear.
Browser fingerprinting alone does not determine all of anonymity. However, when combined with IP address, cookies, login state, time, and post content, it becomes a strong clue.
Related tools
Public IP Check
WhatIsMyIP
An external resource related to this article. Open it only when it fits your situation and threat model.
Why it is listed: It can help with the article topic, but it is outside Anonymity Sense and should be checked before use.