When to use "ibid":
* Same source, same page: If the next footnote or endnote cites the exact same source and page number as the previous one, you can use "ibid" instead of writing out the full citation again.
Example:
* Footnote 1: Smith, John. *The History of Cats*. New York: Penguin, 2005, p. 12.
* Footnote 2: ibid.
When NOT to use "ibid":
* Different source: If the next footnote or endnote refers to a different source, even if it's on the same page, you must write out the full citation.
* Same source, different page: If the next footnote or endnote cites the same source but a different page number, you must write out the full citation, but you can shorten it by using "Ibid." followed by the new page number.
Example:
* Footnote 1: Smith, John. *The History of Cats*. New York: Penguin, 2005, p. 12.
* Footnote 2: Ibid., p. 15.
Formatting:
* "Ibid." is usually italicized.
* It is always followed by a period.
* If a page number is needed, it should be placed after the period, separated by a comma.
Alternatives to "ibid":
* "Idem": Used when the same source is cited, but on a different page.
* "Op. cit.": (Latin for "in the work cited") Used for a source previously cited but not immediately before the current one.
Note: While "ibid" is still used, it's becoming less common, particularly in academic writing. Many style guides recommend using full citations or shortened forms like "idem" or "op. cit."