m-w, my favorite dictionary has improved their site. For instance to find the definition of the word ‘set’ you would simply goto: http://www.m-w.com/dictionary/set There are 35 entries. From hair to sports the word set is very widely used. In math(s) and computer science a set is a collection or container of unique items. Its a bag that contains no duplicates. You could have a set of integers, tv remotes, an empty set, or a set of some other sets. If you are a musician you might play a set...again no duplicate songs. The ocean has waves of waves. If you sit and watch it there are usually a bunch of small waves, then a bunch of bigger ones. Surfers call the group of larger waves a set. This fits the mathematical definition because every wave is completely unique. There is a very interesting game called set. Check out their daily game. Python recently added a set as one of its built in types. >>> a=set() >>> a.add(someobject) A mathematical set doesn't specify an order. They are like a bag or collection. Other mathematical containers such as a list might have an order and even allow duplicates. In this sense a list might have more features and more capabilities. Why limit yourself? In software not limiting yourself means bugs are not discovered until very late in the execution of a program. Without limits along the path of your program it’s hard to know when you have gone off the rails until the cause of the original derailment is lost. Without limits in some other creative medium it becomes very hard to focus. Limits also create a context in which to communicate. Limits are great. This is part of the reason I like sets.