What is the data type 'name' in PostgreSQL

Name is a 63 byte (varchar) type used for storing system identifiers.

Using psql you can get type information using \dT or \dT+

So for the name type:

# \dT name

                           List of data types
   Schema   | Name |                 Description                 
------------+------+---------------------------------------------
 pg_catalog | name | 63-byte type for storing system identifiers
(1 row)

or

# \dT+ name
                                                    List of data types
   Schema   | Name | Internal name | Size | Elements |  Owner   | Access privileges |                 Description                 
------------+------+---------------+------+----------+----------+-------------------+---------------------------------------------
 pg_catalog | name | name          | 64   |          | postgres |                   | 63-byte type for storing system identifiers
(1 row)