Explain: How does a catalyst increase the rate of a reaction?

(N/A) catalyst increases the rate of a reaction. The action of a catalyst can be explained by the intermediate complex theory.
According to this theory,a catalyst participates in a chemical reaction by forming temporary bonds with the reactants,resulting in an intermediate complex.
This intermediate complex has a transitory existence and decomposes to yield products and the catalyst.
It is believed that the catalyst provides an alternate pathway or reaction mechanism by reducing the activation energy between reactants and products,hence lowering the potential energy barrier as shown in the figure.