TLD .net

.net is one of the original top level domains listed in RFC 822, originally intended for network providers. For a time, an attempt was made to keep registrations limited to ISPs and the like, but eventually (a bit later than .com) it was opened up so that anybody could register it, and has sometimes been used by companies who couldn't get their desired name in .com.

It predates by many years the Microsoft framework named .net.