What is the dual table in Oracle?

It's a sort of dummy table with a single record used for selecting when you're not actually interested in the data, but instead want the results of some system function in a select statement:
e.g. select sysdate from dual;
See http://www.adp-gmbh.ch/ora/misc/dual.html

http://stackoverflow.com/questions/73751/what-is-the-dual-table-in-oracle