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;

dual is a table which is created by oracle along with the data dictionary. It consists of exactly one column whose name is dummy and one record. The value of that record is X.

rene@ora92> desc dual
 Name                    Null?    Type
 ----------------------- -------- ----------------
 DUMMY                            VARCHAR2(1)

rene@ora92> select * from dual;

D
-
X

The owner of dual is SYS but dual can be accessed by every user.