Ever since the 1980’s the consensus model used for a long time was called the Practical Byzantine Fault. In simple terms, it helped take a whole bunch of different pieces and draw a conclusion based on the information each piece had. Think of a room with a bunch of people shouting about what they think the answer is.
In 2009, the Nakamoto-era of consensus was launched with Bitcoin. Nakamoto created the Proof of Work mechanism which greatly improved on the old byzantine models. Someone with a super expensive gaming GPU was solving math problems to earn Bitcoin(thanks crypto for making laptops so expensive nowadays) in exchange for melting the polar ice caps.
In 2020, Avalanche launched its own consensus model network. Avalanche is similar to the proof of stake model(where transactions are checked based on how many of that coin is held or staked) but with a few key differences.
It uses something called subsampled voting, which is kind of like jury duty. A few randomly selected people on the network are asked to check transactions at random. Much like jury duty, those participants are then put into a room together, and ‘network gossip’ takes place, where information is exchanged back and forth. The participants eventually conclude whether the transaction is valid ‘guilty or innocent’.
One of the benefits is increased security. Unlike Bitcoin or Ethereum where the network can be attacked if one person holds the majority of the coins(this is called a 51% attack), Avalanche is a lot safer because the jury vets each other as well as the transaction itself, so it requires 80%.
Sub-sampled voting sounds a lot better than checking EVERY transaction, right? What this means is that the network can save a lot of time. Imagine working at a post office but instead of having to send out 10,000 packages, only the packages that couldn’t get automatically sorted were given to you. Now, you finish your job a lot faster.
In terms of blockchain, this means Avalanche has a time-to-finality of fewer than 3 seconds(time the package was received until it was sent off), It can process up to 4500 transactions per second. Bitcoin on the other hand can only process 7 transactions per second with an hour-long finality time.