Oracle Managed Files

Oracle creates and deletes files as needed for tablespaces, temp files, online logs and controlfiles.
OMF and non-OMF files can coexist.
You specify operations in terms of database objects rather than by file names.
Good for low end disks (development environments, NT) and high end (EMC/SAN), not mid range, multi disks.

Parameter files to set
DB_CREATE_FILE_DEST - Location of files
DB_CREATE_ONLINE_LOG_DEST_n default log locations for redo and control files, allows multiplexing with DEST_1, DEST_2 etc.

It is possible to dynamically allocate these with ALTER SYSTEM and ALTER SESSION
ALTER SYSTEM SET DB_CREATE_FILE_DEST = '/u01/oradata/sample';

CREATE TABLESPACE tbs_2 DATAFILE SIZE 400M AUTOEXTEND OFF;
This example creates a tablespace tbs_2 with a datafile in the directory /u01/oradata/sample that is not autoextensible and a size of 400 MB.

A DROP TABLESPACE command will automatically drop non-OMF data files:
DROP TABLESPACE INCLUDING CONTENTS AND DATAFILES;

Also an ALTER DATABASE TEMPFILE can drop the corresponding OS files:
ALTER DATABASE TEMPFILE '...' DROP INCLUDING DATAFILES;