SELECT 
  q_tab.Col_Name As "Name", q_tab.Null_Yn As "Null?", q_tab.Data_Type As "Type", q_tab.comments
FROM 
   (SELECT
      ct.column_id,
      Ct.Column_Name As Col_Name,
      DECODE(ct.nullable,'N','NOT NULL','') as Null_yn,
       RTRIM(SUBSTR(DECODE(ct.data_type,
        'RAW',ct.data_type||'('||ct.data_length||')',
        'VARCHAR2',ct.data_type||'('||ct.data_length||')',
        'CHAR',ct.data_type||'('||ct.data_length||')',
        'NUMBER',ct.data_type|| DECODE(ct.data_precision,NULL,'','('||ct.data_precision||
      DECODE(Nvl(Ct.Data_Scale,0),0,'',','||Ct.Data_Scale)||')'),
      ct.Data_Type),1,20)) As data_Type,
      RTRIM(c.comments) comments
    FROM all_tab_columns ct, all_col_comments c
    WHERE ct.owner = c.owner (+)
    AND ct.table_name = c.table_name (+)
    AND Ct.Column_Name = C.Column_Name (+)
    AND ct.Owner = 'SYS'
    AND ct.Table_Name = Upper('&p_table')
    ORDER BY ct.Column_Id
 ) q_tab;




SELECT 
  q_tab.col_name as "Name", q_tab.null_yn as "Null?", q_tab.data_type as "Type", q_tab.comments
FROM  
  (SELECT
    ct.column_id,
    Ct.Column_Name As Col_Name,
    DECODE(ct.nullable,'N','NOT NULL','') as Null_yn,
    RTRIM(SUBSTR(DECODE(ct.data_type,
     'RAW',ct.data_type||'('||ct.data_length||')',
     'VARCHAR2',ct.data_type||'('||ct.data_length||')',
     'CHAR',ct.data_type||'('||ct.data_length||')',
     'NUMBER',ct.data_type|| DECODE(ct.data_precision,NULL,'','('||
       ct.data_precision||DECODE(Nvl(Ct.Data_Scale,0),0,'',','||Ct.Data_Scale)||')'),
    ct.Data_Type),1,20)) As data_Type,
    RTRIM(c.comments) comments
   FROM
     all_tab_columns ct,
     all_col_comments c
   WHERE ct.owner = c.owner (+)
   AND ct.table_name = c.table_name (+)
   AND ct.column_name = c.column_name (+)
   AND ct.Owner = user
   And ct.Table_Name = Upper('&p_table')
   ORDER BY ct.Column_Id
 ) q_tab;


In oracle database "DESC table_name" shows the column names and their types 
(number, Char(1), varchar2(10), date etc.). The same can done by the above 
scripts. These scripts also gives the column description if defined during 
table creation. This script is for table/view description only. 
The "DESC object_name" will show the object definition of any oracle database 
object.