We can see that events are very closely related to transactions. Indeed, because an event often describes a transaction, it's not uncommon to see the terms used interchangeably. However, events describe a broader class of activity than transactions. Specifically, while events describe a change, transactions capture the recorded elements of the change. Transactions are often the result of an external event—one that does not happen as the result of the action of a particular participant or asset. In this case, a resulting transaction uses a subset of information from the external event as input. But, the event itself is not part of the transaction, other than in this limited sense. This requires a little thought—we're really picking apart some subtle, but important, differences.

In what might appear to be a contradiction, transactions can also generate events! Goodness, this appears to be getting complicated! But think for a moment—events simply describe something happening, and sometimes events are explicitly created by transactions, rather than happening due to a force outside any transaction. In our stock tick example, a transaction might generate an event to signal that the MZK stock has increased by over 5% in a single tick! This event might be Rapid Stock Rise with a structure symbol: MZK, gain: 6.1%—it is explicitly generated by the transaction. The transaction embodies the part of a business process whereby a high percentage stock change is identified and communicated. The event is, in a very real sense, part of the transaction.