The Purpose of Square Brackets in APA
Square brackets in APA citations serve a specific and limited purpose: they signal to the reader that the enclosed information was supplied by the citing author rather than appearing in the original source. In APA 7th edition, square brackets appear in several specific contexts — to describe the format or type of a source, to add clarifying information within a quotation, to supply a missing title for an untitled work, and to distinguish between sources that would otherwise look identical in the in-text citation. Understanding how to use square brackets correctly in APA citations prevents the formatting errors that arise from either omitting them where they are required or inserting them where they do not belong.
Square Brackets for Source Type Descriptors
The most common use of square brackets in APA 7th reference list entries is the source type descriptor — the label that identifies what kind of source is being cited when the source type is not immediately obvious from the reference format alone. These descriptors appear after the title of the work and before the period that closes the title element.
Common source type descriptors in APA 7th include: [Video], [Podcast episode], [Data set], [PowerPoint slides], [Dissertation], [Unpublished doctoral dissertation], [Unpublished master’s thesis], [Photograph], [Map], [Film], [Conference session abstract], and [Poster presentation]. Each descriptor tells the reader something about the nature of the source that the standard citation elements — author, date, title, publisher — do not convey on their own.
The descriptor is italicised or not depending on whether the title it follows is italicised. For standalone works (books, films, datasets) whose titles are italicised, the descriptor in square brackets is not italicised: Title of film [Film]. For component works (journal articles, book chapters, podcast episodes) whose titles are not italicised, the descriptor in square brackets is also not italicised: Title of podcast episode [Podcast episode].
Square Brackets in Direct Quotations
Within direct quotations, square brackets serve a different purpose: they signal editorial additions or changes made by the citing author to the original quoted text. Three specific uses arise in academic writing. First, adding a clarification where the original uses a pronoun whose referent is unclear outside the original context: “They [the doctoral candidates] reported feeling isolated.” Second, correcting an error that appears in the original source without changing the quotation: if the original contains a factual error, you can note this with [sic] immediately after the error — though in most cases it is better to paraphrase an error-containing passage rather than reproducing it. Third, adding emphasis by italicising text that was not italicised in the original, noted with [emphasis added] after the italicised text.
These uses of square brackets within quotations follow the same principle as their use in reference list descriptors: they signal author-supplied content. A reader who sees square brackets in a quotation immediately understands that the bracketed content was not in the original source and was added by the citing author for clarity or correction.
Square Brackets to Supply Missing Titles
When a source has no formal title — an untitled photograph, a data file without a named dataset, a personal letter — APA 7th instructs you to supply a brief descriptive title in square brackets in the title position of the reference: [Photograph of Batu Caves, Kuala Lumpur]. The square brackets signal that this is a supplied description rather than a formal title, preserving the source attribution while acknowledging that no official title exists.
Using square brackets correctly in APA citations is a small but specific competency that signals careful engagement with citation conventions. Incorrect use — such as using round parentheses where square brackets are required, or inserting square brackets where no editorial addition has been made — creates the impression of uncertain familiarity with APA format. A single pass through your reference list and quotation blocks to verify correct bracket use takes only a few minutes but ensures this element of your citation formatting is consistently correct throughout your thesis.
