"An oxidizing agent is a substance in a redox chemical reaction that gains or accepts an electron from a reducing agent."
An oxidizer is any substance that oxidizes another substance and itself gets reduced.
Examples of oxidizing agents include halogens, potassium nitrate, and nitric acid.
The oxidizing power of the halogens decreases on moving down the group from Fluorine to Astatine.
Elemental Fluorine is the strongest common oxidizing agent. is such a good oxidizing agent as the metals and even water burst into flame in its presence.