The if statement in PHP is used to execute a block of code if a certain condition is true. The else statement is used to execute a block of code if the condition is false. Here is an example of how to use the if and else statements in PHP:

$x = 10;

if ($x > 5) {
echo "x is greater than 5";
} else {
echo "x is not greater than 5";
}

In this example, the condition is $x > 5, which evaluates to true. Therefore, the code inside the first block (echo "x is greater than 5") will be executed. If the condition were false, the code inside the else block (echo "x is not greater than 5") would be executed instead.

You can also use the elseif statement to check for multiple conditions. For example:

$x = 10;

if ($x > 15) {
echo "x is greater than 15";
} elseif ($x > 10) {
echo "x is greater than 10 but not greater than 15";
} else {
echo "x is not greater than 10";
}

In this example, the first condition ($x > 15) is false, so the code moves on to the elseif condition ($x > 10). Since this condition is true, the code inside the elseif block (echo "x is greater than 10 but not greater than 15") is executed. If neither the if nor the elseif conditions were true, the code inside the else block (echo "x is not greater than 10") would be executed.