Reactions involving oxidation of one substance & reduction of the other or loss or gain of electrons from an atom.
Cl₂ + H₂S ---------------> 2HCl + S
Oxidizing agents lose oxygen, gain hydrogen and accept electrons. Examples: Cl₂ , O₂ , Concentrated H₂SO₄ & MnO₂ .
Reducing agents gain oxygen, lose hydrogen and donate electrons. Examples: H₂S , H₂ , CO , SO₂ , HCl & Na.