(a) Briefly outline the concept of the Three-tier architecture.

(b) What do you understand by the term Open Source? How does Open Source Software differ from Proprietary Software?

(c) What is the difference between $message and $message?

(d) Find out what the below code snippet prints out:

$age = 12;
$shoe_size = 13;
if ($age > $shoe_size) {
echo "Message 1.";
}
elseif (($shoe_size++) && ($age > 20)) {
echo "Message 2.";
}
else {
echo "Message 3.";
}
echo "Age: $age. Shoe Size: $shoe_size";

(e) What are the three comment syntaxes in PHP? Which one can be used over multiple lines?

(f) Consider the following hyperlink:

< a href="page.php?fname=John&lname=Smith">John Smith

Write down PHP extract codes that will retrieve and write the values of the query string parameters in a Web Page.