What are the differences between using GET and POST methods for passing variables in PHP?

When passing variables in PHP, the main differences between using GET and POST methods are that GET appends the variables to the URL, making them visible in the address bar and limited in size, while POST sends the variables in the HTTP header, keeping them hidden and allowing for larger amounts of data to be transferred securely.

// Using GET method to pass variables
echo '<a href="example.php?name=John&age=25">Click here</a>';

// Using POST method to pass variables
<form action="example.php" method="post">
  <input type="text" name="name">
  <input type="text" name="age">
  <input type="submit" value="Submit">
</form>