A few questions about energy.?

according to llaw conservation of energy " energy can neither be created nor be destroyed" it means that if you are using energy in some form, it is not completely utilised for the same purpose some part is utilised and some part is dissipated. that is converted in to other froms also as there is no ideal machines in the universe. or on the whole you can say energy of the universe is constant you cannot change it. it can only be transformed into other forms knowingly or unknowingly.