From Academic Kids
Relevance is how pertinent, connected, or applicable some information is to a given matter.
In the common law of evidence, "relevance" is tendency of a given item of evidence to prove or disprove one of the legal elements of the case, or to have probative value to make one of the elements of the case likelier or not. Evidence that is irrelevant has no bearing on any of the issues, and the rules of evidence exclude it.
During the 1960s, relevance became a fashionable buzzword, meaning roughly 'relevance to social concerns', such as racial equality, poverty, social justice, world hunger, world economic development, and so on. The implication was that, e.g., the study of medieval poetry and the practice of corporate law were not worthwhile because they did not address pressing social needs.