DNS stands for Domain Name System and is responsible for translating a domain name into an IP address.
Humans recognize domain names like «emubox.ch», but computers only understand IP addresses with which they can communicate with other computers on the network.
Since people can remember letters better than numbers, a system is needed that can convert «emubox.ch» into «204.14.36.60». This way, a computer can find the corresponding server, which can then serve the website for «emubox.ch».