PHP if else

if statement can be used to do a logical comparison.

Simple if statement

if($number > 10){
  echo "number is greater than 10";
}

If statement with two conditions

if($number > 10 ){
  echo "number is greater than 10";
}

Inline if statement or PHP Shorthand If/Else Using Ternary Operators (?:)

( $post_id == $post4->ID)?  'active' :'' 

This is very useful when you want to show some data on HTML pages