A capacitor stores electric charge. Polarised capacitors must be connected the correct way round. They usually have larger values, 1µF and greater. See above for uses.
Thermistor A transducer which converts temperature (heat) to resistance (an electrical property).
Electricity is the flow of charge around a circuit carrying energy from the battery (or power supply) to components such as lamps and motors.
Resistor A resistor restricts the flow of charge. Uses include limiting the current passing through an LED, and slowly charging a capacitor in a timing circuit. Some publications use the old resistor symbol