A set is a collection of well defined members.

The set of vowels is \(a,e,i,o,u.\) The set of the first \(5\) counting numbers is \(1,2,3,4,5.\)

A set is like a list of friend you want to invite to a party.

• If someone's name is on the list they can go in the party. If their name is not on the list they must stay out of the party.
• Nobody is on the list twice.
• The order of the names doesn't matter. Every member is equally important.

Think about the vowels. The list is \(a,e,i,o,u.\) The letter \(b\) is not on the list, so it isn't a vowel. We don't have to list any of the vowels more than once. The order doesn't matter. The set \(i,o,u,a,e\) is also the set of vowels.

Example: Find a set of \(8\) colors.

Think of any colors you can until you get \(8.\) Here is an example, \(red, blue, yellow, black, white, purple, green, pink.\) The set \(red, blue, yellow, black, red, black, yellow, blue\) is not an example. It only has \(4\) colors, it just lists some twice.

If you thought of the set \(blue, yellow, black, white, purple, pink, green, red,\) then you thought of the same set as the example. It is just in a different order.