I\'ve seen some PHP statements that go something like
if($variable) {} or
if(function()) {} (if statements that don\'t compare two variables)
something that may help. You are probably thinking of something like if ($variable < 10), or if ($variable == 'some value'). Just like +, -, /, *, and % these are operators. 1 + 3 returns a value of 4 which is used in the rest of a standard statement. 1 < 3 returns a value of false which is used in the rest of the statement. the if-method accepts a boolean parameter, and executes code if that boolean parameter is true.
notice that:
if (1 < 3) { ... }
is the same as
$myComparison = 1 < 3;
if ($myComparison) { ... }