The if Statement is the simplest conditional statements.

In if  Statements Output will appear when only Condition must be true.

If Statement works  much like the English language statement, “if X happens, then do Y.”

Syntax

if (condition) {
    code to be executed if condition is true;
}

In the example below will output “Have a good day!” if the current time (HOUR) is less than 20:

<?php
$t = date("H");

if ($t < "20") {
    echo "Have a good day!";
}
?> 

Example to find the sum of even number between 1 to 100

<?php
$sum=0;
 
for($i=1;$i<=100;$i++)
{
if($i%2==0)
{
$sum=$sum+$i;
}
}
echo $sum;
?>