I have started using Bitcoins and Block Chain technologies and with the .NET Stack had found the following libraries quite useful.
What is Bitcoins ?
They are nothing more than virtual currencies which are accepted worldwide.They use the Block Chain technology which holds the transaction in distributed servers.
Libraries in C# :
Bitcoin itself is in the initial phase of evolution,there are only few libraries and I am listing the one which was pretty useful for me,
Nicolas Dorier- BitCoin libraries:
BitCoin-Client : https://github.com/NicolasDorier/BlockchainProgramming
BitCoin-Server : https://github.com/NicolasDorier/BlockchainProgramming
GeorgeKimionis-Bitcoin libraries:
https://github.com/GeorgeKimionis/BitcoinLib
They both are transaction oriented.