<human>:  Why does the Green Lantern have a ring?
<bot>: The Green Lantern’s ring is a power source that allows him to create constructs out of willpower. The ring has a green energy core that emits a green glow. The ring was created by the Guardians of the Universe and given to Hal Jordan as a test. Hal Jordan was the first Green Lantern, and he was selected to be the test subject for the ring because he was the most courageous of the test subjects.