significance of MAXLOGFILES, MAXLOGMEMBERS,MAXINSTANCES and MAXDATAFILES in controlfile

what does the terms MAXLOGFILES, MAXLOGMEMBERS,MAXINSTANCES and MAXDATAFILES refers to?
(or)
How to understand control file?

CREATE DATABASE database_1           ---------> indicates the database name
USER SYS IDENTIFIED BY welcome123    ---------> setting the SYS user password
USER SYSTEM IDENTIFIED BY welcome123 ---------> setting the SYSTEM user password
   LOGFILE GROUP 1 ('/u01/database_1/redo01.log') SIZE 100M,
           GROUP 2 ('/u01/database_1/redo02.log') SIZE 100M,
           GROUP 3 ('/u01/database_1/redo03.log') SIZE 100M  ---------> creating redolog groups and members init
   MAXLOGFILES 5           ---------> indicates the maximum number of redo log file groups that can ever be created for the database
   MAXLOGMEMBERS 5         ---------> indicates the maximum number of members for a redo log file group
   MAXINSTANCES  1         ---------> indicates the maximum number of instances that can simultaneously have this database mounted and open.
   MAXDATAFILES 100        ---------> indiactes the maximun nuber of datafiles we can create for database. this value can be changed
   CHARACTER SET US7ASCII  ---------> indicates the character set the database uses to store data
   NATIONAL CHARACTER SET AL16UTF16 --------->  Specify the national character set used to store data in columns specifically defined as NCHAR, NCLOB, or NVARCHAR2
   EXTENT MANAGEMENT LOCAL ---------> Metadata regarding extent allocation and unallocated extents are stored in the tablespace header
   DATAFILE '/u01/database_1/system01.dbf' SIZE 325M         ---------> creation of system datafile
   SYSAUX DATAFILE '/u01/database_1/sysaux01.dbf' SIZE 325M  ---------> creation of sysaux datafile
   DEFAULT TABLESPACE users
      DATAFILE '/u01/database_1/users01.dbf'                
      SIZE 500M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED        ---------> creation of users tablespace and associated datafile with auto extend on option
   DEFAULT TEMPORARY TABLESPACE tempts1                      ---------> creation of temp tablespace and associated temfile
      TEMPFILE '/u01/database_1/temp01.dbf'
      SIZE 20M
   UNDO TABLESPACE undotbs                                   ---------> creation of undo tablespace and associated datafile with auto extend on option
      DATAFILE '/u01/database_1/undotbs01.dbf'
      SIZE 200M  AUTOEXTEND ON MAXSIZE UNLIMITED;
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 cheers....!!!!