哪位高手来解释上这些php配置 代表什么意思

谁来解释下这些php配置 代表什么意思
;
;extension=php_bz2.dll
;extension=php_curl.dll
;extension=php_fileinfo.dll
;extension=php_gd2.dll
;extension=php_gettext.dll
;extension=php_gmp.dll
;extension=php_intl.dll
;extension=php_imap.dll
;extension=php_interbase.dll
;extension=php_ldap.dll
;extension=php_mbstring.dll
;extension=php_exif.dll ; Must be after mbstring as it depends on it
 extension=php_mysql.dll
;extension=php_mysqli.dll
;extension=php_oci8.dll ; Use with Oracle 10gR2 Instant Client
;extension=php_oci8_11g.dll ; Use with Oracle 11gR2 Instant Client
;extension=php_openssl.dll
;extension=php_pdo_firebird.dll
;extension=php_pdo_mysql.dll
;extension=php_pdo_oci.dll
;extension=php_pdo_odbc.dll
;extension=php_pdo_pgsql.dll
;extension=php_pdo_sqlite.dll
;extension=php_pgsql.dll
;extension=php_pspell.dll
;extension=php_shmop.dll

; The MIBS data available in the PHP distribution must be installed. 
; See http://www.php.net/manual/en/snmp.installation.php 
;extension=php_snmp.dll

;extension=php_soap.dll
;extension=php_sockets.dll
extension=php_sqlite3.dll
;extension=php_sybase_ct.dll
;extension=php_tidy.dll
;extension=php_xmlrpc.dll
;extension=php_xsl.dll
;extension=php_zip.dll


------解决方案--------------------
你只开放了
extension=php_mysql.dll ;MySQL 数据库操作函数组
extension=php_sqlite3.dll;SQLite3 数据库操作类

其他的你不使用，也要解释吗？

------解决方案--------------------
给你的链接自己看吧
http://www.php.net/manual/zh/extensions.php