[PHP] what is the point of prepare?

[Hulf]

Hi,

Begining using the php5 mysql functions and want to know what is the point of 
preparing/binding the data before I insert it?

$prep = $mysqli->prepare ("INSERT INTO cd (cdid,title,artist) VALUES 
('0',?,?)");
$prep->bind_param ('22',$title,$artist);

Ta,

R.