What are the best practices for using mod_rewrite in PHP to maintain URL uniqueness and clarity for the server?

When using mod_rewrite in PHP to maintain URL uniqueness and clarity for the server, it is important to create rules that redirect requests to the correct URLs while also ensuring that the URLs are user-friendly and easy to understand. This can help improve SEO and make it easier for users to navigate your website.

```php
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?url=$1 [L]
```
This code snippet sets up a basic mod_rewrite rule that redirects all requests to index.php and passes the requested URL as a parameter. This allows you to handle the request in PHP and generate the appropriate content based on the URL.