AIP Style refers to the citation format established by the American Institute of Physics. AIP is the format commonly used in the field of physics. AIP is a numbered style with references numbered in the order of appearance in the article and listed in that order at the end of the article.
While APA is a more well-known style in general, IEEE is more common in the sciences. You may need to use this style for some assignments. Murdoch University has an especially good research guide with instructions for correct IEEE formatting, and IEEE also has a PDF on their website with citation information.
The Types of Sources tab on this guide refers to an article titled "Female hurricanes are deadlier than male hurricanes." Here is how an in-text citation should look for this article in IEEE:
Researchers hypothesized that a hurricane with a male name would be perceived as more likely to be damaging than a hurricane with a female name, leading people to take more protective action when threatened by a male-named hurricane [1].
The reference list/endnotes in IEEE are organized by the order in which the citations appear in the text, not alphabetically. The reference list entry for the article in IEEE should look like this:
[1] K. Jung, S. Shavitt, M. Viswanathan, and J. M. Hilbe, "Female hurricanes are deadlier than male hurricanes," Proceedings of the National Academy of Sciences, vol. 111, no. 24, pp. 8782-8787, June 2014.
If you cite the same source multiple times in the text, it should have the same number as the first time it appeared, and it should not be entered again in the reference list. In the example above, if I were to cite the same article again later in my paper, I would still use the number [1] as the in-text citation, and I would not need an additional entry in the reference list.