The computer mouse is a pointing device that translates physical hand movement on a surface into cursor movement on screen. Modern optical mice photograph the surface thousands of times per second using a dedicated CMOS image sensor and DSP (Digital Signal Processor), computing the displacement vector between successive frames using cross-correlation algorithms. The core optical tracking pipeline: an LED (infrared or red) illuminates the surface at a low angle. The CMOS sensor captures 4,000–25,000 frames per second at a resolution of 16×16 to 36×36 pixels. The onboard DSP compares consecutive frames, identifies texture patterns, and calculates X/Y displacement with sub-millimeter precision. This computed displacement is reported to the computer at the polling rate — anywhere from 125Hz (8ms intervals) on budget devices to 8000Hz (0.125ms) on flagship gaming mice. DPI (dots per inch) is the most cited but most misunderstood mouse specification. DPI measures how many counts the sensor reports per inch of physical movement. A 1600 DPI setting reports 1600 counts per inch. Higher DPI amplifies small movements into large cursor displacements. For gaming, DPI is meaningless without context — a 400 DPI mouse moved at high speed covers the same screen distance as an 800 DPI mouse moved at half speed. What matters is sensor accuracy at the chosen DPI setting and whether the sensor introduces any acceleration or jitter. Click latency is determined by the switch mechanism. Premium mice use Omron D2FC-F-7N switches rated for 20 million clicks with a mechanical latency of ~1ms. Hall Effect magnetic switches (used in Razer HyperPolling) have no mechanical travel delay. The full click-to-cursor latency pipeline includes switch debounce time (~0.5–4ms), USB polling interval (0.125–8ms), and OS input processing (~1–3ms). Total competitive gaming setups aim for <7ms total input latency. Ergonomics significantly affect performance and health. Palm grip (whole hand rests on mouse) suits larger hands and slower, sweeping movements. Claw grip (only fingertips and palm heel touch mouse) allows faster repositioning. Fingertip grip (only fingertips contact mouse) enables maximum wrist and finger dexterity for low-DPI precise aiming. Weight matters — lighter mice (40–65g) allow faster repositioning; heavier mice (100g+) provide more control for slow movements.