How can the code snippet be optimized for better readability and efficiency in PHP?

The code snippet can be optimized for better readability and efficiency by using proper indentation, comments, and variable naming conventions. Additionally, unnecessary operations can be removed to improve efficiency.

// Original code snippet
$var1="Hello";
$var2="World";
$var3="!";
echo $var1 . " " . $var2 . $var3;
```

```php
// Optimized code snippet
$greeting = "Hello";
$subject = "World";
$punctuation = "!";
echo $greeting . " " . $subject . $punctuation;