capacitors

store charge, smooth ripple, and shape timing. unit: farads (F) — you’ll mostly use nF and µF.

types

• ceramic (MLCC): tiny, low ESR — great for decoupling. use X7R/X5R for bulk decoupling; C0G/NP0 for very stable small values/timing.
• electrolytic (aluminum): polarized, large values (~1–1000 µF), smoothing supplies.
• film: stable, low leakage; nice for audio/timing networks.
• tantalum: polarized, high capacitance/volume; mind surge/over-voltage.

decoupling magic

place a 0.1 µF ceramic as close as possible to each IC’s power pins; add a nearby bulk 10–47 µF per supply area. note: class-II MLCCs (X7R/X5R) lose capacitance under DC bias — pick headroom in value/voltage.

polarity & voltage

• electrolytic stripe = negative lead; the longer lead is usually positive.
• tantalum stripe = positive end on most packages (always check markings).
• choose voltage rating comfortably above the rail; add extra margin if the rail is noisy/spiky.