Trace file and Default tablespace

What is a trace file and how is it created? 

The files that are created when an oracle background process encounters an exception are Trace files.

Processes like dbwr, lgwr, pmon, smon create them.

Trace files are also created by ORA-00600 error or due to some diagnostic dump events

What are Tablespace Quota and default tablespace?

 

A tablespace is a logical storage unit within an Oracle database because it is not visible in the file system of the machine, the database resides on.

The Tablespace quotas are used to assign users with limited size on tablespaces.

Default tablespaces are used for users who are not configured with default tablespaces