What is hydrogenation? What is its industrial application?

(N/A) Hydrogenation is the chemical reaction involving the addition of hydrogen to unsaturated hydrocarbons (such as alkenes or alkynes) in the presence of a catalyst,such as palladium $(Pd)$,platinum $(Pt)$,or nickel $(Ni)$,to produce saturated hydrocarbons.
Example: $CH_2=CH_2$ (Ethene) $+ H_2 \xrightarrow{Ni} CH_3-CH_3$ (Ethane).
Industrial Application: This reaction is widely used in the food industry for the hydrogenation of liquid vegetable oils to produce solid fats like vanaspati ghee.