Creating a User to clarify the 'deffered extent allocation'

SQL> create user venu

                identified by v1;

SQL> grant connect,resource to venu;

SQL> connect venu/v1;

SQL> create table emp(eid number(3));

SQL> desc user_extents;

SQL> set wrap off;

SQL> select segment_name,segment_type,tablespace_name from user_extents;

SQL> insert into emp values(111);

SQL> select segment_name,segment_type,tablespace_name from user_extents;