What are timers and counters in microcontrollers?

Timers count clock pulses to measure time intervals, generate delays, or create periodic interrupts. Counters count external events via an input pin. Most microcontrollers offer dual-function timer/counter units. Common modes include: Timer mode (internal clock), Counter mode (external events), PWM generation, Input capture (measure pulse width), and Output compare (generate precise timing). The 8051 has two 16-bit timers (Timer 0, Timer 1) with multiple modes. Timers are essential for precise timing, PWM, and real-time applications.