Energy is the resource you use to float, light Candles, and generally keep alive. Your Energy is displayed on your Cape, and as a Cape icon in the top-middle of your screen. As you use your Energy it will be drained from your Cape.
When moving, Energy can be used like a jetpack to lift your character higher into the air, from the ground or even while flying. Each time you do this, it will consume a charge of your Energy.
You can restore your Energy by standing next to other players, lit Candles, collecting emotes from Spirits or giving High-Fives and Hugs to your friends.
You can increase the amount of total Energy your character has by collecting the emotes and Winged Light from Spirits around the world. This is indicated by the Cape Icon that appears in the top-middle of the screen or by the diamonds on your characters back that light up. As you level up your cape, you will gain additional charges of Energy.