In what situation is it permissible to omit a citation in APA formatting?

Omitting a citation is permissible in situations where the information is considered common knowledge. Common knowledge refers to facts that are widely accepted and easily verifiable by the general public, such as historical dates or universally known scientific facts. For example, stating that the Earth revolves around the Sun or that World War II ended in 1945 does not require a citation in APA format. This is because these pieces of information are assumed to be known by the audience and do not originate from a specific source that requires acknowledgment.

Conversely, personal opinions, the results of a study, and broad statements generally require citations to give credit to the original sources of the ideas or data presented, as these do not meet the criteria of common knowledge.