Is `DATE` a function?

Hello, Friends,

Use it like a normal function:

playground=# SELECT DATE();
ERROR:  function date() does not exist
LINE 1: SELECT DATE();
               ^
HINT:  No function matches the given name and argument types. You
might need to add explicit type casts.

playground=# SELECT DATE('2022-01-13');
    date
------------
 2022-01-13
(1 row)

Another reason I think this is a function is that other types don't
seem to have the same behavior:

playground=# SELECT integer('123');
ERROR:  syntax error at or near "("
LINE 1: SELECT integer('123');
                      ^

The Table 9.33. Date/Time Functions in the documentation
(https://www.postgresql.org/docs/16/functions-datetime.html#FUNCTIONS-DATETIME-TABLE)
doesn't mention this...
If I missed it, where should I find the description? Or maybe it
actually should be in this table?

Thanks in advance.