Here is a list of all of the sensors and components as well as a reference code, descriptive use, and a link to purchase (warning the internet is a dynamic document, links become outdated. If you happen upon a broken link, please be a kind spirit and modify the link)
LED (Light Emitting Diode) are components that generate light when voltage is applied to them
To use an LED properly you will need a 330? resistor also remember that the longer end should be connected to the Cathode (Positive) end of your circuit.