Discrete selection is often simplified to voltage and current ratings, but real failures frequently involve heat, transients, and layout. MOSFETs require evaluation of on-resistance, gate charge, safe operating area, avalanche capability, and package thermal performance. Diodes and rectifiers require attention to forward voltage, reverse recovery, surge current, and junction temperature. TVS and protection devices must match clamping voltage, pulse power, and interface standards. Diodes groups these products across discrete, protection, and power management families, reflecting how they often work together in input protection and power paths. Selection should include worst-case conditions, thermal boundaries, and certification needs.