Device fingerprinting

Recognizing a device by combining details like its screen size, operating system, fonts, and browser settings into one identifier.

No single detail is unique, but the combination often is, much like how a person might be recognized by a mix of height, voice, and walk.

Derivation of a persistent identifier from device, browser, and network attributes. Persistent means the identifier stays the same across visits, even if the person clears their cookies.

A device fingerprint typically draws on several kinds of attributes:

• Hardware details, such as screen resolution and processor characteristics.
• Software details, such as the operating system, browser version, installed fonts, and language settings.
• Network details, such as the IP address and connection type.

A fingerprinting system typically works like this:

1. The service collects attributes from the device or browser during a session.
2. It combines them into a single identifier.
3. It compares that identifier with those it has seen before.
4. It links sessions and accounts that share the same device.

Fingerprints help in several ways:

• Linking accounts, by showing that one device is behind many accounts.
• Recognizing trusted devices, so familiar customers face less friction.
• Spotting automation, by revealing emulators and scripted browsers.

Device fingerprinting sits next to terms that are easy to mix up:

• Cookies are small files stored on a device, while a fingerprint is calculated from the device's attributes.
• Identity graph links records through shared attributes, including device identifiers.
• Emulator detection identifies simulated devices, which is one use of device attributes.