Oracle "v$" Tables

These tables are known as the virtual tables, v$ tables, dynamic performance tables, and a half a dozen other names. They are tables maintained in memory real-time and store up to date information on the current activity of the database at the current point in time or since the last database startup

the v$ entities are referenced as tables. In actuality the v$ entities are views and each v$ view is a join of two or more x$ tables.

Tables per Category
Backup/Recovery
v$archive
v$backup
v$recovery_log
v$recover_file

Caches
v$db_object_cache
v$library_cache
v$rowcache

Cursors/SQL Statements
v$open_cursor
v$sqlarea
v$sqltext

I/O
v$filestat
v$waitstat

Locks
v$lock
v$_lock

Sessions
v$access
v$process
v$session
v$session_cursor_cache
v$session_event
v$session_wait
v$sesstat
v$sess_io
v$statname