Cryptocurrency — Bitcoin, Altcoins, and Tokens
2.1 — Cryptocurrency: Bitcoin, Altcoin, and Tokens
Recall first. From Module I, a blockchain is a shared ledger, not money itself. What must a digital-cash system prevent if the same digital object can be copied? Write double spending, and one way a blockchain could prevent it, before reading.
The central distinction
A cryptocurrency is a digital asset whose ownership and transfer are controlled by cryptographic keys and the rules of a blockchain or similar distributed ledger. It is not the same thing as the blockchain:
- Blockchain = the ledger, network, and protocol that record and order state changes.
- Cryptocurrency = a digital asset whose units are represented and transferred by that system.
- Bitcoin = the first major cryptocurrency and the native asset of the Bitcoin blockchain.
The book describes cryptocurrency as an encrypted, decentralised digital currency built on blockchain technology and contrasts it with government-issued fiat money. That description is useful for the exam, but “currency” should not make us assume every crypto asset functions well as everyday money: an asset may instead pay for network use, represent a right, or be traded as an investment. [Book: Ch. 3 §3.1, lines 1801–1818]
What makes an asset a coin?
A coin is native to its own blockchain. Its ledger has built-in rules for creating, transferring, and validating that asset. Examples in the book include Bitcoin, Litecoin, Monero, XRP, and Ether; the exact consensus and monetary policy differ by network. A coin can normally be used to pay that network’s transaction fees, although the details depend on the protocol. [Book: Ch. 3 §§3.3.1–3.3.2, lines 1860–1874; §3.4.1, lines 1888–1899]
Bitcoin is therefore both:
- a protocol/network that maintains a public transaction ledger using Proof-of-Work; and
- the name commonly used for its native coin, BTC.
Do not write “Bitcoin is a blockchain” without qualification. A safer exam sentence is: Bitcoin is a cryptocurrency system that uses the Bitcoin blockchain; blockchain is the underlying ledger technology.
Altcoins
Altcoin means an alternative cryptocurrency coin: broadly, any coin other than Bitcoin. An altcoin may be:
- a fork or modified descendant of Bitcoin or another existing project; or
- a coin native to a separately designed blockchain.
The important technical test is not “does it look like Bitcoin?” It is: Does it have its own independent ledger and protocol? If yes, it is a coin/altcoin rather than merely a token. Altcoins may change block times, monetary supply, scripting, privacy, or consensus. [Book: Ch. 3 §3.4.1, lines 1888–1906]
Tokens
A token is a digital asset created on top of an existing blockchain. A smart contract usually defines its balances, transfer rules, and special functions. The token borrows the host chain’s infrastructure and security instead of bootstrapping a new peer-to-peer network, consensus mechanism, and native monetary system from scratch. [Book: Ch. 3 §3.4.2, lines 1907–1924]
A useful analogy:
Blockchain = railway network
Coin = the network's native ticket/fuel
Token = a pass issued by an application using that railwayThe analogy is imperfect, but it preserves the key distinction: a coin belongs to the base network; a token is an application-level asset.
Terminology warning. The book sometimes calls Ether a token because it discusses tokens broadly. For this syllabus, classify ETH as the native coin of Ethereum, while an ERC-20 asset deployed on Ethereum is a token. Always define your terms before classifying an example.
Utility and security tokens
Utility token
A utility token gives its holder a use, access right, or function within a project ecosystem. It may pay for a service, unlock a feature, or provide limited participation rights. The word “utility” describes intended function, not a guarantee that the asset is safe, valuable, or legally exempt from regulation. [Book: Ch. 3 §3.4.2.1, lines 1925–1934]
Security token
A security token represents an investment-like claim, such as equity, profit participation, or another financial right. The book connects it with a Security Token Offering and describes the Howey-style questions: investment of money or assets, expectation of profit, a common enterprise, and reliance on the efforts of others. [Book: Ch. 3 §3.4.2.2, lines 1907–1937]
This is an exam classification, not a universal legal decision. Whether a token is a security depends on the law and facts of the jurisdiction; a project cannot make it non-security merely by naming it “utility.”
| Question | Coin / altcoin | Token | Utility token | Security token |
|---|---|---|---|---|
| Where does it live? | Its own blockchain | Existing host blockchain | Existing host blockchain | Existing host blockchain |
| Main role | Native payment, fees, or value | Application-level asset | Access/use/right in a project | Investment or ownership-like claim |
| Needs its own consensus? | Yes | No; uses host chain | No; uses host chain | No; uses host chain |
| Main exam clue | Independent ledger | Smart contract on another chain | Product/service utility | Profit, equity, or investment expectation |
Forks: where new coins can come from
A fork is a change or divergence in protocol rules. A hard fork is not backward-compatible and may create two independently followed chains; a soft fork is designed to remain compatible with older validation rules. A fork can produce a new coin only when the network and its participants continue a separate history under the changed rules. Merely copying source code does not automatically create a valuable currency: users, validators/miners, wallets, exchanges, and governance must support it. [Book: Ch. 3 §3.3.1, lines 1840–1859]
Worked example — classify four assets
Classify each asset as coin/altcoin, token, utility token, or security token:
- Asset A is created by its own blockchain and pays fees on that chain.
- Asset B is an ERC-20 contract that lets users pay for storage in a decentralised application.
- Asset C is a contract promising holders a proportional share of a company’s profits.
- Asset D is a Bitcoin-derived network with a different block interval and its own miners.
Revealed answer
- Coin (and, if contrasted with Bitcoin, an altcoin): it has an independent ledger and native fee system.
- Token, specifically a utility token: its value/function comes from using the host application.
- Token, specifically a likely security token: it represents an investment-like financial claim. Legal classification still depends on jurisdiction and facts.
- Altcoin: it is an independent blockchain with its own protocol, even though it descended from Bitcoin’s code or design.
Exercise
A project says: “Our token is decentralised because it runs on Ethereum, so investors do not need to examine the project team.” What is wrong with this reasoning?
Revealed answer
The host blockchain may provide ledger infrastructure and consensus, but it does not guarantee that the application, token contract, issuer, governance, economics, or promised service is honest or successful. A token can inherit Ethereum’s transaction security while retaining project-level smart-contract, governance, legal, and market risks.
Exam lens
For a Bitcoin–altcoin–token answer, use this order:
- Define cryptocurrency as a cryptographically controlled digital asset.
- Separate the asset from the blockchain that records it.
- State that Bitcoin is the original cryptocurrency and BTC is its native coin.
- Define an altcoin as a non-Bitcoin coin with its own blockchain.
- Define a token as an asset on an existing blockchain.
- Distinguish utility (use/access) from security (investment/ownership-like claim).
- Add the caveat that legal classification is jurisdiction-dependent.
Common traps:
- Bitcoin is not the same as blockchain.
- “Altcoin” is not a synonym for token.
- A token does not need its own mining network.
- A utility label is not a legal safe harbour.
- “Decentralised” infrastructure does not remove application or issuer risk.
Rapid revision
- Can I define cryptocurrency without calling every crypto asset “money”?
- Can I explain why a coin needs its own blockchain but a token does not?
- Can I classify a token by function rather than by its marketing name?
- Can I distinguish utility from security while leaving legal classification to the jurisdiction?
- Can I explain why Bitcoin is an application of blockchain technology, not a synonym for it?
Key takeaways
- Blockchain is the ledger/protocol; cryptocurrency is a digital asset recorded and controlled through it.
- Bitcoin is the original cryptocurrency and native coin of the Bitcoin blockchain.
- Altcoins are alternative coins with independent blockchains; tokens are issued on an existing blockchain.
- Utility tokens provide project use/access; security tokens represent investment-like claims and may be regulated.
- A host chain can secure token transfers, but it cannot guarantee the token project’s promises.
Sources
- S. Chandramouli, Asha A. George, Abhillash K. A., and Meena Karthikeyan, Blockchain Technology. Primary extract: Ch. 3 §3.1 “Cryptocurrency” (lines 1801–1818); §3.3 “Cryptocurrency” and characteristics (lines 1840–1887); §3.4.1 “Altcoins” (lines 1888–1906); §3.4.2 “Tokens” (lines 1907–1924); §§3.4.2.1–3.4.2.2 “Utility Tokens” and “Security Token” (lines 1907–1937). OCR wording has been silently corrected only where the intended term was clear; historical market counts and prices are not used as current facts.