Heroku app url made out of random words

I'm new to rai开发者_StackOverflow社区ls and heroku, and this may very well seem like a daft question, if so I appologise, but would appreciate someone at least telling me so.

I've followed the heroku "getting started" guide, and managed to deploy a copy of the rails default project. But the url preovided by heroku was http://radiant-ice-84.heroku.com, my question is this:

Does heroku assign a randomly generated url, or have I done something wrong because I don't recognise radiant-ice-84?

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Before you closing this question, I would like to say that you in fact could specify the first when you create the app (no need to change again in the setting page) by using:

heroku create your-app-name

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If you don't specify a name, Heroku generates one for you. You can change it in your app settings (as you noticed), although a lot of people just buy a domain name and map it to the Heroku-generated name.