The system that translates a domain name into the actual server address, like the internet's phone book.
DNS stands for Domain Name System. When a customer types your site's name, their device asks DNS which server address belongs to that name, gets the answer and connects. These answers are configured through records in your domain's control panel, such as one record for the website and another for email.
You will deal with DNS when connecting your domain to hosting, setting up company email or verifying domain ownership for services like Google. A mistake in a single record can take your site offline or send your emails to spam. Practical tip: before changing any record, screenshot or copy the current settings so you can restore them. Remember changes can take time to propagate, so do not keep editing because the first change seems not to work yet.