Ethereum

Changelog.

• v0.2 (2026-10-06; replaces v0.1, sha256 4904395ee43eafb7d1df2ea9cff302dcc003b9aea96c3db3ad28bfd44352e6ea): sourced the smart-contract definition to ethereum.org's introduction to smart contracts, using its wording; described EIP-8038 as updating the cost of accessing state, not only reading it; applied "most" to flagged issues rather than contracts and named the outreach as aimed at the most-affected builders; removed the client-share percentages (a usage figure) and kept the 33% guideline and the page's out-of-date warning; removed an unsupported statement that no newer primary measurement exists; updated four redirecting ethereum.org source URLs to their final addresses; described EIP-8061 as higher exit and consolidation churn and added the ethereum.org Glamsterdam page as the source for faster exits; relabeled the learning hub from "The File" to "Library".

1. What it is

Ethereum is a public blockchain that runs smart contracts, which ethereum.org defines as programs that run on the Ethereum blockchain [12]. Its native currency is ether (ETH), which pays for every transaction [3]. Vitalik Buterin published the introductory white paper in 2013, and the network went live as "Frontier" on July 30, 2015 [1].

Nobody owns Ethereum, and its rules change through an offchain process rather than a token vote [5]. Proposals are written up as Ethereum Improvement Proposals (EIPs), implemented by independent client teams, and bundled into network upgrades [5]. Node operators then choose whether to run the new software [5].

Since September 15, 2022, Ethereum has secured itself with proof-of-stake instead of mining [1]. That switch is known as The Merge [1]. Ethereum is also the settlement layer for many layer-2 (L2) networks, which execute transactions elsewhere and post their data back to Ethereum [4]. Two of the Library's other dives, Arbitrum and Robinhood Chain, are L2s of this kind.

2. How it works

Two halves: execution and consensus

An Ethereum node runs two pieces of software [2]. The execution client handles transactions and the Ethereum Virtual Machine (EVM) [2]. The consensus client handles proof-of-stake [2]. A validator also runs a third piece, the validator client [2]. Since The Merge, the two layers upgrade together, which is why upgrades carry paired names such as "Pectra" (Prague plus Electra) [1].

Several teams write these clients independently [5]. At the execution layer they include go-ethereum, Nethermind, Besu, Erigon and Reth [5]. At the consensus layer they include Prysm, Lighthouse, Nimbus, Teku, Lodestar and Grandine [5].

Proof-of-stake

To become a validator, a user deposits 32 ETH into the deposit contract and joins an activation queue [2]. Time is divided into 12-second slots, and 32 slots make an epoch [2]. In each slot one validator is chosen at random to propose a block, and a committee of validators votes on it [2]. These votes are called attestations [2].

A block becomes final through checkpoints [2]. When validators holding at least two-thirds of all staked ETH vote for a pair of checkpoints, the earlier one is finalized [2]. Reverting a finalized block would require an attacker to lose at least one-third of all staked ETH [2]. If the chain fails to finalize for more than four epochs, an "inactivity leak" drains stake from validators who are not voting with the majority, so the chain can recover [2].

Validators that break the rules are slashed [2]. The two slashable offenses are proposing two blocks in one slot and making contradictory attestations [2]. The penalty grows with the number of validators slashed around the same time, from under 0.1% of stake for an isolated case up to the whole stake in a mass event [2].

Fees

Every operation costs gas, and gas is paid in ETH [3]. A transaction pays a base fee set by the protocol plus an optional priority fee, or tip, for the validator [3]. The base fee is burned [3]. It moves up or down by at most 12.5% per block, depending on whether the previous block was above or below its target size, which is half the gas limit [3]. This fee design came from EIP-1559, part of the London upgrade of August 5, 2021 [1].

Blobs and layer 2s

L2 rollups post their transaction data to Ethereum so that the data inherits Ethereum's security [4]. Since the Dencun upgrade of March 13, 2024, they can post it as "blobs", a cheaper data type that is kept only for a limited time [1]. This change is EIP-4844, also called proto-danksharding [1].

The Fusaka upgrade of December 3, 2025 added PeerDAS [1][7]. Under PeerDAS, a full node no longer downloads every blob [7]. Each node holds a share of the data, and the network can rebuild any blob from half of the pieces [7]. Fusaka also lets clients raise blob capacity through small "blob-parameter-only" forks between major upgrades [7].

3. What changed

Pectra (May 7, 2025). EIP-7251 raised the maximum effective balance of a single validator to 2,048 ETH [1]. EIP-7002 let a withdrawal address trigger exits directly [1]. EIP-7702 lets an ordinary account run code like a smart contract, which allows features such as batched transactions and gas sponsorship [1].

Fusaka (December 3, 2025). Besides PeerDAS, Fusaka capped any single transaction at 16,777,216 gas (2^24) [7]. It set a 10 MiB ceiling on block size [7]. It also added a precompile for the secp256r1 curve, which lets wallets use device passkeys [7]. Client teams shipped a 60 million default gas limit with it [7]. The Ethereum Foundation says Fusaka raised the mainnet gas limit "on the path to 200M and beyond" [10].

Glamsterdam (next). Glamsterdam combines the Amsterdam execution upgrade with the Gloas consensus upgrade [9]. Its two headline changes are [8][9]:

• Enshrined proposer-builder separation (ePBS, EIP-7732). Today, validators who outsource block building rely on third-party relays outside the protocol [8]. ePBS moves the hand-off and the builder's payment into the protocol [8][9]. Ethereum.org says it widens the window for spreading block data from about 2 seconds to about 9 seconds [8].
• Block-level access lists (EIP-7928). Each block records which accounts and storage slots it touches [9]. Clients can then read state and validate transactions in parallel [9].

Glamsterdam also reprices gas [9]. EIP-8037 raises the cost of creating new state, and EIP-8038 updates the cost of accessing it [9][11]. Ethereum.org says EIP-8037 targets state growth of 120 GiB a year [8]. The Foundation warns that a small set of existing contracts may break or degrade under the new schedule without updates [11]. Other scheduled changes include ETH transfers emitting a log (EIP-7708) and higher exit and consolidation churn, which ethereum.org says lets stakers exit faster (EIP-8061) [8][9].

Glamsterdam was scheduled to activate on the Sepolia testnet on October 6, 2026 at 13:53:36 UTC, 6:53 a.m. Phoenix time [9]. The Foundation's announcement says mainnet and Hoodi dates "have not yet been decided" [9]. Ethereum.org lists mainnet as expected in Q4 2026, "date not yet confirmed" [8].

4. What is open

Glamsterdam's mainnet date and final scope. No mainnet date has been set [9]. Ethereum.org says scope "is frozen but can still change before mainnet, as the meta EIP remains in draft" [8]. The Foundation calls a 200 million gas limit a "credible post-Glamsterdam target" [10]. On Sepolia, at least two consensus clients default to 60 million gas after the fork unless validators set 200 million themselves [9].

Contract breakage from repricing. The Foundation found that replaying past mainnet transactions under the new gas schedule flags a small set of contracts that may break or degrade [11]. Most flagged issues can be fixed with a higher gas limit, and outreach to the most-affected builders is under way [11]. How many affected contracts will be updated before mainnet is not known.

Relays until ePBS ships. Until ePBS is live, proposers who outsource block building depend on off-protocol relays and trust between parties [8]. Even after ePBS, builders and proposers "might still choose to use off-protocol relays" for features the protocol does not cover [8].

Client concentration. A bug in a consensus client run by more than a third of nodes could stop finality [6]. A bug in a client with a two-thirds share could finalize an invalid chain [6]. Ethereum.org says that, ideally, no consensus client would reach a 33% share of nodes, and warns that its own client-share snapshot may be out of date [6].

Offchain governance. Upgrades depend on rough consensus among client teams, node operators and users, with no binding vote [5]. That makes contested changes slow by design [5]. It also means "who decides" has no single answer.

Staff changes at the Foundation. In May 2026 the Foundation's Protocol cluster said two coordinators were leaving and a third was going on sabbatical, during preparation for Glamsterdam [10]. The effect on delivery timelines, if any, is not stated.

What this page leaves out. By Library policy, this dive carries no price, market value, staking-yield or usage-volume figures. Those go stale, and News covers them.

Not financial advice.