The SLDs that are managed by Nominet UK are:
.co.uk for commercial enterprises (the largest SLD in the UK)
.me.uk for personal domains
.org.uk for non-commercial organisations
.ltd and .plc for registered company names only
.net.uk for Internet Service Providers
.sch.uk for schools
The term "second level" here is more of a technical thing. It's actually up to individual NICs to decide how to create their own hierarchies. Most ccTLDs did not have top level domain (e.g. .ca, .cn, .hk), it's only recently that the demand for shorter and more competitive (vs. .com) domains has actually driven these country level NIC to change. Who knows? Perhaps UK will be next in line.mark said:i went to the site nic.uk as indicated above and it says that
co.uk is a second level domain. i always thought it was top level and in reality it is, at least for the commercial aspect.