Glossary
Constantinople Hard Fork
The February 2019 Ethereum upgrade that lowered block rewards, added new opcodes (CREATE2, EXTCODEHASH), and reduced gas costs for several frequently-used operations.
Constantinople activated on Ethereum mainnet on February 28, 2019, at block 7,280,000 (after a delay from January due to a discovered reentrancy issue in EIP-1283). The fork introduced CREATE2 — the deterministic-address deployment opcode now used across factory patterns and account abstraction — and reduced block rewards from 3 to 2 ETH.
The fork's bundled EIPs (145, 1014, 1052, 1234) also lowered gas for bit-shift operations and added EXTCODEHASH for cheaper contract introspection. Constantinople was one of the foundational "complex EVM" upgrades that enabled the patterns DeFi later relied on.