finite sets has a limit
ex:
a.(discription) O={x/x is an ood number less than 20}
b.(roster) {1,3,5,7,9,11,13,17,19}
we do not define set,as it is an intuitive concept.A set may be thought of as a collection of objects.these object are called elements or members of the set.
ex:
a set of integers
a set of point
and etc.
Subsets
There are cases where two or more sets contain some,but not all of the same elements.Consider the set of positive even numbers,A={2,4,6,8,...},and the set of positive whole numbers,B={1,2,3,4,...}.
so we say that A is a subset of B
An infinite set is a set whose elements can not be counted. An infinite set is one that has no last element. An infinite set is a set that can be placed into a one-to-one correspondence with a proper subset of itself.
sorry if I dont give the other meeanings/description of your questions because I'm not so famillar of it :)