Transfinite numbers are one of Cantor's ordinal numbers , , , ..., , , ... all of which are "larger" than
any whole number.
As noted by Cantor in the 1870s, while it is possible to distinguish different levels of infinity, most of the details of this have not been widely used in typical mathematics.
However, transfinite numbers can be helpful in studying foundational issues (Wolfram
2002, p. 1162).