Capacitors store charge and present a frequency-dependent impedance. Pick type by voltage, ripple or AC current, ESR, and package.
Ceramic (MLCC)
Small, low ESL, ideal for HF bypass at IC power pins. Watch DC bias derating on small case sizes. See the ceramic capacitor category guide for dielectric codes (X7R, C0G).
Electrolytic (aluminum, polymer)
High bulk capacitance for input and output banks on regulators and audio supplies. Polarized: observe polarity and ripple current rating. The electrolytic category guide covers lifetime and ESR.
Film
Stable, low loss for timing, filters, and mains-rated applications where ceramics are too small. Less common on digital power rails than MLCC plus electrolytic pairs.
Use the capacitor calculator for energy storage estimates and the reactance calculator for impedance at a frequency.