(1) For unsolicited software, see
parasite.
(2) In the electronic world, parasitics are undesirable characteristics resulting from electricity flowing through circuits. Resistance (unwanted obstruction), capacitance (unwanted charge) and inductance (unwanted magnetic field) are the three parasitics that can cause timing issues, signal degradation, interference and loss of power. "Parasitic extraction" comprises methods to lessen parasitics in circuits.