For most science concepts I try to intuitively understand what a quantity actually *is* but I'm having trouble understanding enthalpy. I understand the definition and how to work the standard problems you see involving H but I don't intuitively understand what it is. In other words, why is it that H=E+PV? Since enthalpy is usually used to describe a general concept of "energy," (in a reaction), why add the PV work instead of just using E? I hope you understand what I'm trying to say, any help would be appreciated.