A #WebPrivacy tip.

Fingerprinting is the act of trying to covertly identify a user or distinguish one user from another by reading stuff about their setup. Web sites and web browsers can do this, and your job as a developer is to protect your users from it. #stuartwriting 1/5

One way to think about fingerprinting is as active vs passive. A passive fingerprinting technique is one which uses information that is given to the website by default; an active technique is one which explicitly interrogates the browser for extra information. #stuartwriting 2/5

Browser vendors know that users do not like being tracked, and are continually implementing features to limit fingerprinting. Active fingerprinting techniques are harder because browsers pop up confirmation dialogs: this stops the fingerprinting being covert! #stuartwriting 3/5

In practice, most developers and most businesses have no need to fingerprint users. If you require users to sign in, then they identify themselves to you, with consent, and in a way that they can unilaterally opt out of at any time they choose. This protects their privacy. #stuartwriting 4/5