7 - PHP:Introduction - If statement
We're already familiar with the concepts of the control statements as we learned in JavaScript. They behave basically the same, but since they are in different languages, the syntax can be a little different.
The following example will output "Have a nice weekend!" if the current day is Friday, otherwise it will output "Have a nice day!":
<html>
<body><?php
$d=date("D");
if ($d=="Fri")
echo "Have a nice weekend!";
else
echo "Have a nice day!";
?></body>
</html>
If more than one line should be executed when a condition is true, the lines should be enclosed within curly braces:
<html>
<body><?php
$x=10;
if ($x==10) // notice one = sign assigns a value to a variable, two compares
values.
{
echo "Hello<br />";
echo "Good morning<br />";
}
?></body>
</html>
(from w3schools.com)