Overview of Ethereum Milestones?

Question

In 2017 there was the Metropolis hardfork. In 2018 there will be Constantinople.

• Is Constantinople a full PoS fork or will it be hybrid like 1 block of 200 will be PoS mined?
• Will there be a Casper fork after Constantinople?

Can somebody please point me to a description of what these forks exactly plan to do and what the current development stage of the parts of Constantinople is?

Answer 1

Metropolis is not a fork but a milestone in the Ethereum roadmap. Simplified:

• Proof of Concept 1-8 (ETH 0.1) were several implementations of the Ethereum protocol in 2014 and 2015.
• Olympic (ETH 0.9) was the last proof-of-concept testnet for Ethereum prior to the mainnet launch (2015).
• Frontier (ETH 1.0) was the beta phase and the launch of the Ethereum mainnet (2015).
• Homestead (ETH 1.1) was the switch to an stable Ethereum mainnet (2016).
• Metropolis (ETH 1.2) is where are are currently at. It's a phase of balancing and improving the protocol. Metropolis contained several hardforks so far:
  • Byzantium (2017)
  • Constantinople (2019)
  • Istanbul (2019)
• Ethereum 1.x (ETH 1.x) is a term that will contain many features preparing for the transition to ETH 2.0. Arguably the Berlin fork might be the first one fitting into this category.
  • Berlin (scheduled for 2020)
  • ...
• Ethereum 2.0 (ETH 2.0, Serenity, Casper, ...) contains the actual switch to Proof-of-Stake. It's organized by phases (scheduled for 2020).
  • Phase 0 (ETH 2.0) is the beacon chain allowing for staking Ether.
  • Phase 1 (ETH 2.1) is the sharding extension allowing to horizontally scale Ethereum.
    • In a subsequent step, the legacy ETH 1.x chain will become a shard in Phase 1, sometimes referred to as Phase 1.5.
  • Phase 2 (ETH 2.2) will add the execution environments to the other shards allowing for contract deployment and application development on the shard chains.

I hope that answers your questions.