Primary storage, also known as main memory or RAM (Random Access Memory), is the computer's short-term memory. It temporarily holds data and instructions that the CPU (Central Processing Unit) needs while performing tasks. This allows for quick access and processing, making the computer run efficiently. When a computer is turned off, the data in primary storage is lost, as it is volatile memory. In contrast, secondary storage, like hard drives and SSDs (Solid State Drives), retains data even when powered down. Primary storage is essential for running applications and managing active processes in real-time.