Diode polarity refers to the positive and negative terminals of each diode, according to SparkFun. All diodes are polarized. The positive end is known as the anode, and the negative end is called the cathode.
Diode polarity refers to the fact that an electrical current is only able to flow through a diode in a single direction, from the anode to the cathode. SparkFun notes that it is essential to connect a diode at the right end for this reason, because the electrical current would otherwise be unable to flow. All diodes have a physical indicator to show which side is the anode and which side is the cathode, making it easy to ensure proper diode polarity.
According to All About Circuits, being able to determine the polarity of a diode is an essential skill for all electronics technicians to have. Although polarity only flows in one direction, a common mistake among new technicians is not to recognize that there are two types of polarity, cathode and anode. Polarity is easily tested by connecting a battery-powered ohmmeter to one side of a diode. Technicians then monitor the level of resistance to determine if the diode is of cathode or anode polarity.