Polkadot: The Network Built to Connect Other Blockchains
Most blockchains operate in isolation from each other. Polkadot was built specifically to let them talk, and that design choice shapes everything else about it.
By Firoz Khan|14 August 2026|Updated 11 October 2026|3 min read
Most blockchains are built as self-contained systems, Bitcoin can't natively talk to Ethereum, and vice versa. Polkadot was designed specifically to solve that isolation problem, functioning as a network of networks rather than a single chain trying to do everything itself.
The relay chain and parachain structure
Polkadot's core, the relay chain, provides shared security and coordination for a set of connected, independent blockchains called parachains, each of which can be optimised for its own specific purpose, a payments chain, a smart contract chain, a gaming chain, while still benefiting from the relay chain's shared security rather than having to bootstrap its own from scratch.
Polkadot's documentation says the relay chain has deliberately minimal functionality. Its primary purpose is to facilitate block production, core scheduling and data availability, and to provide shared security. Parachains connected to it all share in its security, which also means that if the relay chain reverts, all connected parachains revert as well. Parachains communicate with each other using XCM, cross-consensus messages.
Why shared security is the actual innovation
A brand new, small blockchain launched independently is genuinely vulnerable, it simply doesn't have enough validators securing it yet to stand up to a serious attack. A parachain connecting to Polkadot inherits the security of the entire relay chain's validator set immediately, a meaningfully different security proposition to launching alone.
How DOT, the native token, is actually used
DOT is used for network governance, staking to help secure the relay chain, and historically for parachain slot auctions, where projects bonded DOT to win a limited, time-based connection slot to the network. That auction model has evolved over time as the project's approach to onboarding new parachains has developed.
The documentation now describes the system in terms of execution cores, similar to processor cores. Projects can use a dedicated parachain with a permanent core, or an on-demand parachain that shares cores, and both require buying coretime with DOT. It also says that the relay chain no longer supports user-facing functions. Accounts, balance transfers and staking have been moved to a chain called Polkadot Hub, which was called Asset Hub until its late-2025 rebrand.
Polkadot Hub: where most people now interact
Polkadot's documentation describes Polkadot Hub as the main entry point to the network. It lists holding and sending DOT, staking, governance and identity among the things you can do there, along with smart contracts written in Ethereum-style languages such as Solidity, and the creation of tokens and NFTs.
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The documentation says fees for asset transactions are approximately one-tenth of the cost of relay chain transactions, and that fees can be paid in assets other than DOT. Treat that as the project's own description, not a promise about future cost.
How coretime works
Polkadot sells block-production capacity as coretime. Its learning wiki describes two ways to buy it. Bulk coretime is bought in fixed periods, currently 28 days, and is represented by an NFT that can be split, shared or resold. On-demand coretime is bought close to real time for a single block, with the price rising as the queue grows and a minimum price below which it cannot fall. The wiki's worked price examples come from Kusama, Polkadot's sister network, so no Polkadot prices are quoted here.
How this differs from Ethereum's layer-2 approach
Ethereum scales by letting separate rollups post their data back to Ethereum and rely on its security. Polkadot takes a different route: parachains share the relay chain's security by design and talk to each other using XCM messages. Neither is simply better. Polkadot's route needs coretime and fitting its framework, while Ethereum's rollups each carry their own bridge and upgrade rules.
Questions people ask
- Is DOT backed by anything? No. It is a native network token whose price moves like other crypto, and the FCA says to be prepared to lose all the money you put in.
- Do parachains share the same security? They inherit the relay chain's security, as described above.
- Where do I check current instructions? In Polkadot's own documentation, because the structure of the network has changed more than once.
Holding DOT in the UK
For UK tax, DOT is treated like other tokens: HMRC treats each type of token as its own pool with its own pooled cost, and swapping it for another cryptoasset is a disposal. If you stake, HMRC's guidance says that unless the activity amounts to a trade, the sterling value of rewards when you receive them is taxable as miscellaneous income. The FCA says crypto is largely unregulated in the UK and that you should be prepared to lose all the money you put in.
The trade-off worth understanding
Interoperability and shared security come at the cost of real complexity, both technical and conceptual, compared to a simpler, self-contained single-chain design. Polkadot's bet is that a genuinely multi-chain future needs this connective infrastructure; whether that bet pays off depends on how much of the wider blockchain ecosystem actually ends up needing this specific kind of interoperability.
Because staking and accounts have moved to Polkadot Hub, guides written before that change can be out of date. Before staking or moving DOT, check the current instructions in Polkadot's own documentation or your wallet's help pages, and confirm which chain your balance sits on.
Where to read more
- Layer-2 blockchains explained: the Ethereum approach to scaling
- Proof of work vs proof of stake: how a network is secured
- Ethereum's Pectra upgrade explained: a comparison with another major upgrade
- Crypto taxes in the UK: staking and disposals
A reminder
The FCA risk warning still applies to higher-risk crypto content. Always assess how much risk you are willing to take before buying.
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