The reactivity series orders metals by how vigorously they react:
Potassium > Sodium > Lithium > Calcium > Magnesium > Aluminium > Carbon > Zinc > Iron > Hydrogen > Copper > Silver > Gold
A more reactive metal can displace a less reactive metal from its compound. E.g.: Zinc + Copper sulfate → Zinc sulfate + Copper
Metals above carbon in the reactivity series are extracted by electrolysis. Metals below carbon are extracted by reduction with carbon.