Here is a visual so you have a better idea: 0 Payments with 0 confirmations can still be reversed! If you want to keep track of precisely when these halvings will occur, you can consult the Bitcoin Clock , which updates this information in real time. Quite simply, the longest valid chain becomes the official version of events. The results are bound to be interesting; perhaps even the beginning of a profound technological shift in how we conduct our lives and business!