Meagan Longoria deals with the unpleasantness:
Although you can now specify an Oracle database using the EzConnect format, it’s still very common to use a tnsnames.ora file. This file specifies a connection name and connection details for an Oracle database. It’s helpful in that you can provide a “friendly name” to the database specified in the file and then reference the file from multiple client tools.
Read on to learn how you can use it.