This is really technical, but interesting on many levels. Waltz is a write-ahead log. When you submit a transaction, your submission is written to the write-ahead log before it is entered into the database and any instructions executed. That way, if the system fails during the database activity, there is a record of what you did. Like other write-ahead log systems, this one accepts input from multiple systems, creating a single point of reference for multiple types of transaction. What's new in Waltz is that it checks the transaction for consistency before it is entered into the log. This enables the log, rather than the databases, to be the source of truth for these multiple systems. The article as a whole describes how this is implemented in detail, but unless you're a database aficionado, this summary should suffice to keep you abreast of the terminology and technology.