Discrimination of diode pin polarity

The diode circuit graphic symbol is printed on the housing. One side of the vertical line is the negative electrode of the diode, and the other end is the positive electrode of the diode.

A diode marked with a colored ring on the housing. One end of the colored ring is the negative electrode, and the other end is the positive electrode of the diode.

There is a difference in the length of LED pins, with the longer end being the positive electrode.

A high-power diode with a threaded end for the negative electrode and the other end for the positive electrode.

The rectifier diode is usually marked with a white ring on the black housing, with one end being the negative electrode and the other end being the positive electrode.