Why a companion app exists at all
A hardware wallet on its own is a small device with a screen and a couple of buttons. It can sign transactions and display addresses, but it is not designed to browse balances, fetch exchange rates, or organize dozens of accounts. Those tasks belong to software running on a bigger screen. The companion app fills that gap.
When you want to send funds, the app assembles the unsigned transaction — the recipient, the amount, the network fee — and passes it to the hardware wallet. The device shows you the details on its own trusted display, you verify them, and only then does it produce a signature. The signed transaction goes back to the app, which broadcasts it to the network. At no point does the computer see the private key, which is why malware on the computer cannot silently drain the wallet: it would still need physical confirmation on the device, and the device shows the real destination address independently of whatever the computer claims.
This "trust the screen, not the computer" model is the heart of hardware-wallet security, and understanding it makes every feature in Trezor Suite easier to reason about.
Continue with the official documentation
For current requirements and instructions about the roles of software and hardware, consult the official Trezor documentation before proceeding.
Visit the official Trezor Suite page