The concept of a set emerged in mathematics at the end of the 19th century. The German word for set, Menge, was coined by Bernard Bolzano in his work Paradoxes of the Infinite.
Georg Cantor,

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Mathematical texts commonly denote sets by capital letters in italic, such as A, B, C. A set may also be called a collection or family, especially when its elements are themselves sets.
Roster notation
Roster or enumeration

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If B is a set and x is an element of B, this is written in shorthand as x ∈ B, which can also be read as "x belongs to B", or "x is in B". The statement "y is not an element of B" is written as y ∉ B, which can also be read as or "y is not in B".
For example, with respect

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A singleton set is a set with exactly one element; such a set may also be called a unit set. Any such set can be written as {x}, where x is the element. The set {x} and the element x mean different

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If every element of set A is also in B, then A is described as being a subset of B, or contained in B, written A ⊆ B, or B ⊇ A. The latter notation may be read B contains A, B includes A, or B is a

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An Euler diagramis a graphical representation of a collection of sets; each set is depicted as a planar region enclosed by a loop, with its

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The empty set (or null set) is the unique set that has no members. It is denoted ∅ or or { } or ϕ (or ϕ).

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