The Utils class is the base class and holds a bunch of essential methods for dealing with input and creating or manipulating data.
The methods have input for user data because they don't do anything with the data on their own, they accept the user input and use it that way.
This is run when you create the class. It attempts to connect to the database, and if it cannot then it stops everything by throwing errors
$dbnameThe name of the database you want to use in this instanct of UserSystem
This either returns nothing or throws this error: "DB_* constants in config.php failed to connect to a database. " and then whatever PDO has to add.