DNS stands for Domain Name System and is essentially the act of converting your domain name into a numeric address ("IP Address") that computers connected to the Internet can understand, and vice versa.
Every time a website is requested, a lookup is performed to see which IP address that domain name is pointing to. To speed things up for repeat visitors, this result is stored in several places ("cached") for a specific period of time so that this check is not constantly and unnecessarily performed.
Whenever DNS is modified, we must wait for this cached record to be updated with the new details. This procedure is called propagation and though it usually occurs in a matter of minutes, may take anywhere up to 72 hours to successfully complete. DNS can be cached in several places, including your local ISP, so the exact propagation time depends on many factors beyond our control.
