What is an oxidation reaction? Explain it with an example.

An oxidation reaction is defined as a chemical process in which oxygen or an electronegative element is added to a substance,or hydrogen or an electropositive element is removed from a substance.
Examples:
$1$. Addition of oxygen:
$2 Mg_{(s)} + O_{2(g)} \rightarrow 2 MgO_{(s)}$
$S_{(s)} + O_{2(g)} \rightarrow SO_{2(g)}$
In these reactions,$Mg$ and $S$ are oxidized due to the addition of oxygen.
$2$. Addition of an electronegative element:
$Mg_{(s)} + F_{2(g)} \rightarrow MgF_{2(s)}$
$Mg_{(s)} + Cl_{2(g)} \rightarrow MgCl_{2(s)}$
$3$. Removal of an electropositive element:
$2 K_{4}[Fe(CN)_{6}]_{(aq)} + H_{2}O_{2(aq)} \rightarrow 2 K_{3}[Fe(CN)_{6}]_{(aq)} + 2 KOH_{(aq)}$
In this reaction,the removal of the electropositive element $K$ from potassium ferrocyanide is an oxidation process.