“A set A is a subset of a set B… [if] all elements of A are also elements of B.” (“Subset,” Wikipedia, retrieved 6/17/2020, emphasis added)
For some more terminology, here’s the complete quote if you are interested:
“In mathematics, a set A is a subset of a set B, or equivalently B is a superset of A, if A is contained in B. That is, all elements of A are also elements of B. A and B may be equal; if they are unequal, then A is a proper subset of B. The relationship of one set being a subset of another is called inclusion or sometimes containment.” (Ibid.)
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Disclaimer:
I am not a professional in this field, nor do I claim to know all of the jargon that is typically used in this field. I am not summarizing my sources; I simply read from a variety of websites until I feel like I understand enough about a topic to move on to what I actually wanted to learn. By definition, none of these posts address every aspect of a topic. If I am inaccurate in what I say or you know a better, simpler way to explain a concept, I would be happy to hear from you :).
