A range is simply a group of cells. For example, the cells A1, A2, A3, A4, A5 can be referred to individually when using them in a formula but it is quicker to use a range. The following formulas, which give the same result, demonstrate this:
=SUM(A1, A2, A3, A4, A5)
=SUM(A1..A5)
You can give a cell range a unique name and refer to it in formulas using the name, rather than specifying the first and last cells in the range. You can also treat fields in a database table as ranges so that, for example, you can sum all the records in an invoice database.
See also: