Historical archive · 2021 · 17 briefings
17 original, source-linked historical crypto briefings associated with events or proposals documented in 2021. Articles were published Sep 28, 2026.
Ethereum · Historical retrospective · 2021
Altair activated on the proof-of-stake Beacon Chain in October 2021, updating consensus rules and validator accounting before the Merge.
Read the briefing →Layer 2 · Historical retrospective · 2021
Arbitrum One launched as an Ethereum scaling network using optimistic execution and a dispute process for posted state transitions.
Read the briefing →Security · Historical retrospective · 2021
Audits can identify classes of implementation risk, but they are point-in-time reviews of a defined code version and scope.
Read the briefing →Ethereum · Historical retrospective · 2021
Berlin activated in April 2021 and included changes that adjusted gas costs and introduced an optional access-list transaction type.
Read the briefing →Bitcoin · Historical retrospective · 2021
BIP 327 defines a multi-signature protocol that combines participant keys and signatures into a single Schnorr signature under specified assumptions.
Read the briefing →Bitcoin · Historical retrospective · 2021
BIP 86 proposes a standard path for single-key Taproot accounts derived from a hierarchical wallet seed.
Read the briefing →Policy · Historical retrospective · 2021
El Salvador’s Legislative Assembly approved a law in 2021 that gave Bitcoin legal-tender status alongside the U.S. dollar, under the law’s specified terms.
Read the briefing →Ethereum · Historical retrospective · 2021
The August 2021 London upgrade introduced a base fee that adjusts with block demand, alongside an optional priority fee for users seeking faster inclusion.
Read the briefing →NFTs · Historical retrospective · 2021
As NFT trading expanded, marketplaces differed on whether creator royalties should be mandatory, optional or enforced through contract design.
Read the briefing →NFTs · Historical retrospective · 2021
NFT contracts commonly point to metadata that may live outside the blockchain, including on web servers or content-addressed storage systems.
Read the briefing →Layer 2 · Historical retrospective · 2021
Optimism’s early mainnet era brought EVM-compatible optimistic rollup execution to applications seeking lower costs than Ethereum mainnet.
Read the briefing →Stablecoins · Historical retrospective · 2021
As stablecoins grew into major trading and settlement instruments, questions about reserve composition, custody and verification became more prominent.
Read the briefing →Security · Historical retrospective · 2021
In August 2021 Poly Network reported an exploit affecting assets across multiple chains, with the incident centered on how cross-chain messages and privileged keys were validated.
Read the briefing →Policy · Historical retrospective · 2021
A 2021 President’s Working Group report discussed stablecoin arrangements and recommended congressional action on issuer oversight and systemic risks.
Read the briefing →DeFi · Historical retrospective · 2021
Uniswap v3 introduced concentrated liquidity, allowing providers to allocate capital within selected price ranges instead of across the full curve.
Read the briefing →DeFi · Historical retrospective · 2021
Concentrated-liquidity positions in Uniswap v3 use non-fungible tokens to encode a provider’s chosen price range and liquidity parameters.
Read the briefing →NFTs · Historical retrospective · 2021
Common token interfaces such as ERC-721 allowed wallets and marketplaces to discover ownership and support transfers across many collections.
Read the briefing →Event or proposal year: 2021. These retrospective articles were first published Sep 28, 2026.