Bitcoin · Historical retrospective · 2015
BIP 125 documented opt-in transaction replacement policy
BIP 125 describes rules under which an unconfirmed transaction can signal that a higher-fee replacement may supersede it.
Read the briefing →Historical archive · 2015 · 7 briefings
Crypto milestones in 2015
7 original, source-linked historical crypto briefings associated with events or proposals documented in 2015. Articles were published Sep 28, 2026.
Bitcoin · Historical retrospective · 2015
BIP 141 proposed Segregated Witness transaction accounting
BIP 141 defines SegWit’s witness-data structure and a block-weight limit that accounts for signature data differently from the traditional block-size measure.
Read the briefing →Bitcoin · Historical retrospective · 2015
BIP 65 added a consensus-enforced absolute time lock
BIP 65 redefined the OP_CHECKLOCKTIMEVERIFY opcode so scripts could require a transaction to wait until a specified block height or time.
Read the briefing →Bitcoin · Historical retrospective · 2015
BIP 68 introduced relative sequence-based time locks
BIP 68 gives transaction input sequence numbers a relative-locktime meaning, measured from the confirmation of the referenced output.
Read the briefing →Ethereum · Historical retrospective · 2015
EIP-165 standardized smart-contract interface detection
EIP-165 defines a way for a contract to report which interfaces it supports through interface identifiers.
Read the briefing →Ethereum · Historical retrospective · 2015
ERC-20 gave fungible Ethereum tokens a shared interface
EIP-20 defines common token methods and events, allowing wallets, exchanges and contracts to interact with many assets in a consistent way.
Read the briefing →Ethereum · Historical retrospective · 2015
Ethereum Frontier opened the first live mainnet era
Frontier was Ethereum’s initial mainnet phase, enabling developers to deploy contracts and interact with the network while the ecosystem was still experimental.
Read the briefing →Event or proposal year: 2015. These retrospective articles were first published Sep 28, 2026.