There are various sources of informations about the law, but they are not all of equal authority. One important distinction made between legal sources is between 'primary' and 'secondary' sources.
Primary sources are those that originate directly from a body with a recognised law-making authority. Examples of primary sources are legislation and case law.
Secondary sources are those that originate from a body that has no direct law-making authority. Examples include legal commentaries, articles and textbooks.