How can PHP developers improve their coding practices when passing variables through links?

When passing variables through links in PHP, developers should sanitize and validate the input to prevent security vulnerabilities such as SQL injection or cross-site scripting attacks. One way to improve coding practices is to use PHP's built-in functions like `htmlspecialchars()` to encode the variables before outputting them in the link.

// Sanitize and validate the variable before passing it through a link
$variable = isset($_GET['variable']) ? htmlspecialchars($_GET['variable']) : '';

// Output the variable in a link
echo '<a href="page.php?variable=' . $variable . '">Link</a>';