How can incorrect syntax in PHP code, such as missing double quotes or incorrect array references, impact the execution of code blocks?

Incorrect syntax in PHP code can lead to syntax errors, which can prevent the code from executing properly. Common mistakes include missing double quotes around strings, incorrect array references, or mismatched parentheses. To fix syntax errors, carefully review the code for any missing or misplaced syntax elements and make the necessary corrections.

// Incorrect syntax example: missing double quotes
$name = John; // missing double quotes around the string

// Corrected code with double quotes added
$name = "John";