Bitcoin (BTC) is classed by the US Federal Gov't (IRS) as property, not currency.
That wasn't some kind of mistake or tax technicality on the IRS' part - a lot of analysis went into this in 2013, along with DHS and FinCEN. This is the definition for BTC in the US.
That means what happened today could be described as: The first and oldest decentralized, distributed, cryptographically-secured record of digital property ownership (Bitcoin as a network) is producing cryptographic keys (the property, BTC) at half the rate it was yesterday. There is now less of the digital property (BTC) being created by the network daily, and this is due to an artificial scarcity strategy built into the Bitcoin source.
Hope that helps