Bitcoin is a peer-to-peer electronic cash system that is completely decentralized, without the need for a central server or trusted parties. Users hold the crypto keys to their own money and transact directly with each other, with the help of a P2P network to check for double-spending.
OpenTeacher is a vocabulary training application that helps you learn a foreign language. It uses a list of words in both a known and a foreign language and tests you. It supports smart question asking and interval training with Think answers, shuffle answer, and repeat answer input modes. It has easy symbol, Greek, and Cyrillic input, and reads and writes T2K (Teach2000) and WRTS files, and reads ABBYY Lingvo Tutor files. It is available in Arabic, Australian English, Brazilian Portuguese, Chinese (Traditional), Croatian, Czech, Danish, Dutch, French, German, Hebrew, Hungarian, Japanese, Korean, Polish, Russian, Serbian, Slovenian, Spanish, Swedish, and Turkish.