What are the main purpose of regulatory policies and its examples

To give government the ability to control (or "regulate") activities of people. Every government regulation and regulatory agency came into existence because somebody saw a problem in society requiring a solution by the government.

For example, in the early part of the 20th century in the U.S. people became concerned because of substances being sold to the public for consumption that were unsafe. There were dangers in contaminated food, and in so-called medicines that had no value in curing disease and might even make you sick. To address concerns over these unsafe products the Congress established the Food and Drug Administration, which establishes inspection requirements for food and drugs, as well as testing for drugs for safety before they are sold to the public.

Regulation doesn't just apply to companies. Cars are dangerous machines that require skill and knowledge to operate safely. My father started driving when he was 12 years old, before there were any licensing requirements to operate an automobile. After he became an adult he had to go to DMV because the state passed a law requiring drivers to fulfill certain requirements in order to drive on a public road. While I'm sure my dad loved driving at the age of 12, I don't think it's safe to let 12-year-olds drive on the streets.

Also in the early part of the last century the new technology of radio became widespread. Oddly enough, the technology wasn't that complicated to a lot of people, and hobbyists could build transmitters without a lot of difficulty. The problem is, the amount of bandwidth in the air is finite, and there isn't enough of that finite resource to accommodate everybody who might want to transmit. Therefore, a Federal Communications Commission was created to regulate the airwaves. Similar agencies were created in every country in the world. Without such regulation to allocate bandwidth to various uses and among transmitters (including commercial broadcasters), radio and television couldn't operate effectively, with competing users ramping up the power of their signals to drown each other out.

Regulatory policy is one of the things we need from government to make society function. Letting the government "control" or "regulate" certain aspects of our life may sound like tyranny. However, unless people abide by conventions enforced by the government, we'd be selling each other poison, dumping our garbage and sewage in the streets, being run over by incompetent drivers (worse than we are now), and generally be in a state of nature (the jungle) rather than a civilization.

Is it just free response or do you have multiple choice?