The oxidizing agent is known to be a type of reactant that will remove the electron from other available reactants. This means that the oxidizing agent will be getting the electrons for itself so that it will gain electrons. Some people would refer to oxidizing agents as the oxidants of oxidizers. Some of the things that you are familiar with are oxidizing agents.
Oxygen has to be the most common. Aside from this, the different halogens and hydrogen peroxide are also oxidizing agents. When oxidizing agents are added to different things, you can expect that they will react with whatever it is added to. This explains why wounds that are cleaned with hydrogen peroxide may start to bubble.