If you saw this error in the browser during WordPress installation:
Your PHP installation appears to be missing the MySQL extension which is required by WordPress.
That's because WordPress requires MySQL extension of PHP to access the database.
php-mysqlnd
In this moment, you need to install php-mysqlnd module.
[root@web ~]# yum -y install php-mysqlnd
For Debian distros, you can use apt-get to install this module.
No worry about the abstraction layer of database connection, the dependency module php-pdo will be installed as well.