https://www.php.net/manual/en/refs.international.php
https://www.php.net/manual/en/refs.fileprocess.file.php
https://www.php.net/manual/en/refs.calendar.php
https://www.php.net/manual/en/refs.database.php
https://www.php.net/manual/en/refs.crypto.php
https://www.php.net/manual/en/refs.compression.php
https://www.php.net/manual/en/refs.utilspec.cmdline.php
https://www.php.net/manual/en/refs.remote.auth.php
https://www.php.net/manual/en/refs.utilspec.audio.php
https://www.php.net/manual/en/refs.basic.php.php
PHP: Function Reference - Manual
https://www.php.net/manual/en/features.dtrace.php
https://www.php.net/manual/en/features.gc.php
https://www.php.net/manual/en/features.commandline.php
https://www.php.net/manual/en/features.persistent-connections.php
https://www.php.net/manual/en/features.connection-handling.php
https://www.php.net/manual/en/features.remote-files.php
https://www.php.net/manual/en/features.file-upload.php
https://www.php.net/manual/en/features.xforms.php
https://www.php.net/manual/en/features.sessions.php
https://www.php.net/manual/en/features.cookies.php
https://www.php.net/manual/en/features.http-auth.php
https://www.php.net/manual/en/features.php
https://www.php.net/manual/en/security.current.php
https://www.php.net/manual/en/security.hiding.php
https://www.php.net/manual/en/security.variables.php
PHP: Error Reporting - Manual
https://www.php.net/manual/en/security.database.php
https://www.php.net/manual/en/security.filesystem.php
https://www.php.net/manual/en/security.sessions.php