How can PHP handle ISO-8859 encoding for special characters like umlauts?

To handle ISO-8859 encoding for special characters like umlauts in PHP, you can use the `utf8_encode()` function to convert the string from ISO-8859-1 to UTF-8 encoding. This function will properly encode special characters like umlauts, making sure they are displayed correctly.

// Sample string with ISO-8859-1 encoding
$isoString = "Müller";

// Convert ISO-8859-1 to UTF-8 encoding
$utf8String = utf8_encode($isoString);

// Output the UTF-8 encoded string
echo $utf8String;