What PoW hashing algorithms did Monero historically use?

Question

Originally, Monero used the Cryptonight PoW algorithm, then started modifying it to thwart ASICs getting large parts of the network hash rate.

What is the timeline of these changes ?

Answer 1

Monero's genesis block dates back from April 2014. The first PoW change was in 2018.

The full history is:

| block   | date       | PoW algorithm
|---------|------------|--------------
| 0       | 2014-04-18 | Cryptonight (retroactively CNv0)
| 1546000 | 2018-04-06 | Cryptonight variant 1 (CNv1)
| 1685555 | 2018-10-18 | Cryptonight variant 2 (CNv2)
| 1788000 | 2019-03-09 | Cryptonight variant 4 (CNv4)
| 1978433 | 2019-11-30 | RandomX

Monero switched to RandomX in November 2019, a new PoW algorithm not based on Cryptonight, which is based on the premise of random code execution.