Customizing your WordPress login page is one of the cool thing and is the part of white-labeling your website.
Two main reasons for customizing your WordPress login page includes:
Branding: If you put your identity logo on the top of login form makes look like something custom designed building.
Security: By adding additional security check, it protects you from hackers and bot to break website and steal information.
There are lot of premium and free plugins that can do these customization’s. No matter what plugin or way you can use, its very easy.