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GNU Taler v1.0 released
(www.taler.net)
If it's free and open source and it's also software, it can be discussed here. Subcommunity of Technology.
This community's icon was made by Aaron Schneider, under the CC-BY-NC-SA 4.0 license.
It can be many different ones. Usually your home bank would allow you to exchange some Euro into Taler tokens and then use those to pay in compatible stores. But instead of a centralized system there can be many different exchanges that follow the same standard (protocol) and can be used with the same software and wallet apps.