Ask HN: Why do many websites use a country code as the top-level domain?

Many top-level domains correspond to a specific country code, such as .ie or .nz. I'm familiar with the .com, .edu, .org, .gov convention used in the United States, so using the country code as the top domain seems pointless and confusing to me. For example, for a long time CERN used cern.ch despite the fact that they're located in both France and Switzerland.

Why is this the current practice?