Specific Heat Capacity

Specific heat capacity is defined as:

$E = mc\Delta\theta$

where $E$ is the energy transferred (J), $m$ is the mass (kg), $c$ is the specific heat capacity (J/(kg $^\circ$C)), and $\Delta\theta$ is the temperature change.

Water has a high specific heat capacity (4200 J/(kg $^\circ$C)), which is why it is used in cooling systems and central heating. Metals have much lower values (e.g. aluminium: 900, copper: 390).

A high specific heat capacity means the substance needs a lot of energy to heat up, and releases a lot of energy when cooling down.