In your own words provide a brief definition of user access control (UAC). Does it do any good or complicate things?

In your own words provide a brief definition of user access control (UAC). Does it do any good or complicate things? Is a software vendor’s lack of adequate security a violation of ethics? Is it a fiscal decision? Do vendors have a responsibility to their shareholders?– No plag– 350-400 words only– 3 citations.