A trusted execution environment (TEE) is a secure area within a computer's processor that ensures sensitive data is processed in a protected manner. It creates a safe space where applications can run without interference from other software, including the operating system. This isolation helps protect against various security threats, such as malware. TEEs are commonly used in devices like smartphones and tablets to safeguard personal information, such as passwords and payment details. Technologies like Intel's Software Guard Extensions (SGX) and ARM's TrustZone are examples of how TEEs are implemented in modern computing systems.