What is a Fireball? As in games or magic. Is it a ball of flaming air? Doesn't fire need fuel to burn? If it's air then how do you throw a ball of air and make air stay in that ball shape? Why'd you be hit by a ball of air? Why'd it explode on impact instead of just softly spread?

"I'm not expert but id say the "magic" is the fuel, the magic is manipulated forward and on impact it suddenly releases outwards creating an explosion. Infact there are plenty of "rookie" fireball using people who's fireball skills aren't refined so when they use it the fireball does gently spread or even extinguish rather then explode in movies and books and such. "