Here are 3 reasons for gTLDs that come to mind. (I'm late to the scene, and there are plenty of pioneers around who can provide a better answer): 1: Without so

Here are 3 reasons for gTLDs that come to mind. (I'm late to the scene, and there are plenty of pioneers around who can provide a better answer): 1: Without some sort of naming convention websites would be a string of numbers. This was what the one we ended up with, and we are all used to it now. 2: The TLDs provide the first port of call for looking up a url. Thus the .com DNS server needs to know al the .coms, but that is it. the 2LD servers likewise have to deal in their area only. That's a lot easier than storing and refreshing the entire authorized internet DNS lookup at all points. (I'm getting out of my depth here, but there is some pretty clever stuff going on these days) 3: As you say the TLDs provide basic 'segregation' and while .net and .com use cases seem to have merged, .gov, .mil and beyond that country ccTLDs such as .uk, .nz and .au are all performing important roles for now and for a long time going forward. Meanwhile there are 7 billion people, and goodness knows how many businesses in the world, and many of them have similar names. Different TLDs and 2LDs give them a chance to coexist. Yahoo and other giant corporations are a bit different as they are truly global and need to buy up all domains, but most companies are not interested in every last TLD. The money made from the gTLD and 2LDs goes towards supporting the DNS system, which is what makes the internet work, SOPA notwithstanding.