What is the main purpose of science?

The main purpose of science is to expand the human knowledge. Science is all about logic and rational as compared to religion which is mostly based on belief, and where logic and rationality play smaller roles.

Science isn't focused on looking at things from the philosophical point of view but from empirical point of view where data can be verified with different tests and methods.

Science has experienced significant development in the last century or so, but some vital questions such as the question about the origin of life still remain a huge mystery for scientists.

No matter how much science develops it will still be unable to find the answer to all questions. This, however, can not be looked at as something negative but more like a force that drives science forward, in search of new, important knowledge.

In some cases, it is very difficult to determine the boundaries of science, or to put it in other words how much is science allowed to go, and what is considered unethical (for instance the question of cloning people).

Like everything else science also needs some regulations because uncontrolled science could cause many negative things, doing quite the opposite of what science should really stand for, namely constantly improving human well-being.

Science today isn't the same as the science 2000 years ago was but some principles remain the same. The human knowledge constantly grows but with more knowledge there comes even more mysteries and unsolved questions, so science is always going forward.

Science tries to add more certainties into the uncertain world by having some well-defined and highly applicable laws (such as Newton's laws for motion, Einstein's relativity theory, etc).

Scientists do this by gathering empirical evidence to create rational hypothesis and theories that explain certain phenomenons. Gathering empirical evidence cannot be done without the constant experimenting so science is basically "a never-ending experiment that tries to establish causality between things".