Connecting to MySQL-database

I'm creating a WWW-page in开发者_如何学Go www.freehostingcloud.com. I created a database of the name sample. But how can I connect to it in MySQL and PHP? I saw from PHP.net that I should type

mysqli = new mysqli('localhost', 'my_user', 'my_password', 'my_db');

OK, so my_db=sample but what are those parameters 'localhost', 'my_user' and 'my_password'?

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They are the host, username and password required to access your database. Localhost means your computer aka 127.0.0.1, the others are the users you create in your local db.

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They are documented in the Parameters section of mysqli::__construct().