In physical equations, the amount of heat transferred is usually denoted with the symbol Q.
Heat vs. TemperatureNote this crucial component to the above definition:
Heat always refers to the transfer of energy between systems (or bodies), not to energy contained within the systems (or bodies).This can be very confusing, because we're used to in day-to-day conversation talking about heat as if it's contained in something. This distinction between heat and temperature is subtle, but very important.
Example: The iron is hot, so it's reasonable to say it must have a lot of heat in it. Reasonable, but wrong. It's more appropriate to say that it has a lot of energy in it (i.e. it has a high temperature), and touching it will cause that energy to transfer to your hand ... in the form of heat.