Atlas wallets use Multi-Party Computation (MPC) technology for greater protection against on-chain attacks. With MPC wallets, the private key used for signing transactions is split into shares and encrypted within isolated secure hardware enclaves across multiple cloud environments.
Transactions are signed through multiple rounds of computation using these key shares, without the full private key ever being brought together in a single environment. This removes the single point of compromise associated with private key creation and signing.
In summary, your private key is never stored in one place. Instead, it is split into parts and kept securely in separate systems, so no single party can access or control it on their own.