The essential components of a computer system include the central processing unit (CPU), memory (RAM), storage devices (HDDs/SSDs), and input/output (I/O) devices. The CPU executes instructions and processes data, while RAM temporarily holds data for quick access. Storage devices retain data long-term and enable the retrieval of files and applications. I/O devices, such as keyboards, mice, and monitors, facilitate user interaction with the computer. Additionally, a motherboard connects all these components, allowing them to communicate and function as a cohesive system.