There are two types of Synonyms Private and Public.
The set of Redo Log files YSDATE,UID,USER or USERENV SQL functions, or the pseudo columns LEVEL or ROWNUM.
Each Index has an Index segment that stores all of its data
Each databases logically divided into one or more tablespaces one or more data files are explicitly created for each tablespace.
Data Segment, Index Segment, Rollback Segment and Temporary Segment.