Top level domain is the part of an Internet address/URL after the dot in, for example, dot com .COM. In my case here, quackofdawn.com, the com is the TLD.
We’re used to seeing .NET, .ORG and countries TLDs but not too many more.
A whole slew of new TLDs will be released some time [soon?] … not just a few, but hundreds of them.
I was reading an article about this, and by chance I noticed that one of all those TLDs was .DUCK! I thought I might like that … if for nothing else, it would have been …. unusual, but it turns out that whole domain was applied for by a corporation [S C Johnson, manufacturers of hosehold products]. So … no .duck for me.