A couple of days earlier, on February 20, Cardano succeeded in implementing a hard fork called Ouroboros BFT. The network now runs on a better consensus mechanism. What is more, this is a big step towards implementing Shelley on the network. A recent blog post published on Medium explains why.
When Cardano spread the word about the hard fork launch on Twitter three days ago, it said that this upgrade was to “pave the way for the Shelley mainnet release.”
UPDATE: #Cardano OBFT hard fork successfully completed! ? ? ?— Cardano Community (@Cardano) February 21, 2020
Cardano recently underwent a mainnet hard fork (=software protocol update) on 20-02-2020, during epoch 176, to pave the way for the "#Shelley" mainnet release. pic.twitter.com/Uemla5AKoG
So far, the mainnet uses Ouroboros ‘Classic’ – this a PoS consensus protocol. Although, Cardano users cannot vote for validators and choose those themselves.
Once Shelley arrives, the situation will change and these restrictions will be removed – users will get a chance to elect validators by staking their ADA tokens. Shelley will be launched in two steps so as the network remains intact, without any interruptions.
Initially, Shelley was planned to launch back in late 2019. But the team face several major setbacks and had to handle those. Now, the exact date of the release is vague so far but there is information that Shelley will be launched at some point in Q1 this year.