Supply Side Economics is a theory that states that economic prosperity can be best achieved by lowering taxes, promoting private businesses and minimal government intervention.
All the above appealed to conservatives since they want deregulation of industries, freer and open markets, they wanted to end labor unions and promote Private businesses, both small and large.
One of the most popular and arguably successful proponents of supply-side economics of President Ronald Regan who lowered taxes which eventually lead to more investments and job creation.