Ethereum hard forked today with 2 hard forks in Constantinople and St. Petersburg. They both happened today on Block 7,280,000 and represent both a fix and some optimization improvement for Ethereum. Most users should not notice the difference except Miners who saw their rewards per Block go down from 3 to 2. This is a temporary measure until Ethereum Serenity updates the Blockchain to Proof of Stake and replaces the miners with Validators and marks the transition from proof of work to proof of stake.
