The EPOC or "afterburn-effect" refers to the number of calories you burn after your workout to bring your body back to its normal resting state.
One study shows a slight elevation of 7% in resting energy expenditure (REE) for up to 72 hours after resistance exercise in untrained individuals, however In trained individuals, a 2013 study suggests this effect is insignificant.
Evidence for cardio for the afterburn effect shows the higher the intensity, the greater post-exercise REE.
In short, what most of us know as the "afterburn-effect" exists and often does slightly contribute to your daily energy expenditure, but it's far from the secret of fat loss. The actual additional caloric expenditure that is achieved is quite small generally 7-14% of the energy expended during exercise and therefore is not enough to put you in a caloric deficit on its own.