What is the difference between a process and a thread?

A **process** is an independent program instance with its own memory space. A **thread** is a lightweight execution unit within a process that shares memory with other threads. **Processes:** better isolation; IPC needed for communication. **Threads:** cheaper context switching; need synchronization to avoid race conditions. **Interview tip:** Mention that multi-threading can boost throughput but introduces complexity (locks, deadlocks, contention).