Tuple

In mathematics, a tuple is a finite sequence of objects. Sometimes, the finite sequence is also called an ordered list. This means that the order of the objects matter. In a tuple, the objects are either enclosed within parentheses (such as ), or within angle brackets (such as ).  Each of the objects in the list has a certain type. A tuple consisting of n entries is called an n-tuple. Tuples are used to describe mathematical objects that are made of certain, well-defined components. They are also used very frequently with databases. 
Tuples are different from sets:
A certain element can be in a tuple more than once.
The order in which the elements appear in a tuple is important.

In other words, tuples are like ordered multisets.

 Related pages 

 Relation (mathematics)

 References 

Category:Set theory