GETS, GETHITS, PINS, PINHITS -- Differences???

Guys, I am really confused between these terms. Could someone here shed some light with very precise and complete differences between the following:

I
------
GETS,

GETHITS,

PINS,

PINHITS wrt LIBRARY CACHE




II
----------
GETS,

GETMISSES,

SCANS,

SCANMISSES wrt ROWCACHE


I read a few articles, but they all seem to confuse me as each varies in its precise definition. Thanks in advance for your time and patience.

V$ROWCACHE -
GETS column represents the total number of times a process or Oracle asked for the item named in the column PARAMETER.
GETMISSES column represents the number of times a request for dictionary information couldn't find that information in the dictionary cache and instead had to go to the SYSTEM tablespace to retrieve the information.
SCANS column is the number of scan requests.
SCANMISSES column is the times a scan failed to find the data in the cache.

V$LIBRARYCACHE -
GETS columns is the number of times a lock was requested for objects of this namespace.
GETHITS column is the number of times an object's handle was found in memory.
PINS column is the times a PIN was requested for objects of this namespace.
PINHITS column is the number of times all of the metadata pieces of the library object were found in memory.