When Windows 8.1 is installed, it automatically downloads and installs all the available drivers. However, some of them require a manual installation. To install or update drivers on Windows 8.1, you need to visit the official website of the manufacturer and download the compatible version for your OS.
To automatically keep your drivers up-to-date, you can use a third party tool like Driver Magician. This will automatically search and download all the latest drivers compatible with your hardware.