What is an Analog-to-Digital Converter (ADC) and what are its key parameters?

An ADC converts continuous analog signals to discrete digital values. Key parameters include: resolution (number of bits, determines smallest detectable change - 12-bit ADC has 4096 levels), sampling rate (conversions per second, must satisfy Nyquist criterion - sample at >2x highest frequency), accuracy (deviation from ideal transfer function), linearity (how closely steps match), and input range. Common types include SAR (successive approximation), sigma-delta (high resolution), and flash (high speed). ADCs are fundamental to all digital measurement systems.