build.prop
Also called: build properties, build fingerprint
build.prop is the Android system file holding the device’s build properties — manufacturer, brand, model, product name, Android version, build ID and build fingerprint. Apps read these values to know what device they are running on, which makes the file a central part of any device identity.
Located at /system/build.prop, the file is a plain list of key-value pairs written when the firmware is built. The keys that matter most to an app are ro.product.manufacturer, ro.product.brand, ro.product.model, ro.build.version.release and ro.build.fingerprint — the last being a single string that concatenates brand, product, device, version and build type.
The consistency requirement
These values are read together, and they have to agree with each other and with the hardware. A build fingerprint naming a Samsung Galaxy S23 while ro.product.manufacturer says Google is broken on its face. Subtler: a build ID that never shipped for the model claimed, or an Android version the model never received, are both detectable by anyone maintaining a table of real firmware releases.
They must also agree with the device fingerprint as a whole. A build.prop claiming a flagship on a device reporting a 720p screen and 2 GB of RAM contradicts itself.
Why editing it is not enough
Rewriting build.prop changes what the device says about itself, not what it is. Sensors, baseband, GPU strings, codec lists and battery behaviour all continue reporting the real hardware underneath. This is the ceiling every spoofing approach hits, and the reason real hardware with genuinely different build properties behaves differently from one device pretending to be many.