The WordPress login screen is well designed – it's clean and simple to interact with and it works well on all screen sizes. But what if you're building a site for a client who wants to display their own logo to users logging in? Or if you have a MultiSite installation and want your users to see your branding when they log in? Luckily, you can customise the way the login screen looks quite easily.
Another useful tutorial to consider is our Envato Studio resources on WordPress Customization. It's a different technique, but something that's equally handy to know!