FAQ

By strict definition, a Ponzi scheme pays earlier participants with later participants' money and is run deceptively by a central operator. Bitcoin has no central operator and promises no fixed returns; its code and ledger are publicly auditable. Critics, however, argue that its price depends heavily on new buyers and is highly volatile, and the debate continues.
Source: Investor.gov (US SEC)

Yes. Bitcoin's Proof-of-Work mining consumes substantial electricity — annual estimates are roughly comparable to a mid-sized country, though figures vary widely across sources. Supporters note some mining uses otherwise-wasted or renewable energy; critics emphasize the carbon footprint. The energy use is real; how one weighs it differs.
Source: Cambridge CBECI

It is pseudonymous, not anonymous. Every transaction is permanently recorded on a public blockchain; addresses carry no real name, but once an address is linked to an identity (e.g., through an exchange's identity checks), its history can be traced. "Bitcoin is untraceable" is a common misconception.
Source: bitcoin.org · Protect your privacy

A blockchain is a distributed ledger maintained by many parties, where transactions are grouped into "blocks" ordered in time and cryptographically chained together. Once recorded, altering past data is computationally very hard, giving it strong tamper resistance. It does not rely on a single central authority to validate records.
Source: Bitcoin whitepaper · Original: bitcoin.org

A smart contract is program code deployed on a blockchain that executes automatically when preset conditions are met, carrying out agreed logic (e.g., "if X is received, send Y") without an intermediary. Note: the code is the rule, so bugs execute just as automatically — many past losses stemmed from contract flaws.
Source: ethereum.org

Bitcoin was designed primarily as a peer-to-peer electronic cash / store-of-value network with a focused feature set. Ethereum is a general-purpose programmable platform supporting smart contracts and decentralized apps, with ETH as its native token. Also, Bitcoin uses Proof-of-Work, while Ethereum switched to Proof-of-Stake in 2022.
Source: ethereum.org

Stablecoins aim to hold a 1:1 peg (usually to the US dollar), but "stable" does not mean "risk-free." Risk depends on whether reserves are genuinely sufficient and auditable, and on the mechanism — fiat-collateralized types rely on issuer and custody; algorithmic ones have collapsed off-peg before (e.g., the 2022 Terra/UST event). Safety must be assessed case by case.
Source: ethereum.org

An NFT is a unique on-chain record of ownership. Buying one generally gives you the on-chain record of holding that token — not necessarily the copyright, commercial rights, or the media file itself; actual rights depend on the project's terms. The image is often stored off-chain and can become inaccessible if the link breaks. This is widely misunderstood.
Source: ethereum.org

DeFi replaces traditional intermediaries with smart contracts. Key risks: exploitable contract bugs, oracle manipulation, "impermanent loss" when providing liquidity, and the absence of traditional regulation or deposit insurance. There is no customer support or undo button — mistakes are usually irreversible. High potential yields typically come with high risk.
Source: ethereum.org

A gas fee pays for the computational resources needed to execute a transaction or run a smart contract on chains like Ethereum; on Ethereum, the base fee is burned and only the priority tip goes to the validator. It fluctuates with congestion — busier means more expensive.
Source: ethereum.org

If your private key (or seed phrase) is permanently lost with no backup, the assets in that wallet generally become permanently inaccessible — no central authority can recover or reset it, the core trait of self-custody. A meaningful share of all Bitcoin is estimated to be permanently locked due to lost keys (exact figures vary). Backing up your seed phrase safely is critical.
Source: bitcoin.org · Securing your wallet

Web3 is a vision for a "next generation of the internet" centered on using blockchain and related tech to give users more ownership over their data and digital assets, reducing reliance on a few large platforms. It is an evolving, loosely defined concept — proponents see a decentralized future, critics question how decentralized and mature it really is.
Source: ethereum.org

No. Blockchain is the underlying technology (a distributed ledger maintained by many parties); cryptocurrency is just its earliest and best-known application. Blockchain also powers smart contracts, supply chains, identity and more; conversely, some digital currencies do not rely on a public blockchain.
Source: NIST IR 8202 · Original: nist.gov

An airdrop is a free distribution of tokens to eligible wallet addresses, often to reward early users, decentralize governance, or for marketing. Be careful: many "airdrops" are phishing scams — those asking for your seed phrase/private key, pushing you to sign unclear approvals (e.g. unlimited token approvals), or asking you to prepay a "fee" to an unknown address are almost always fraudulent; verify the URL via the project's official channels before claiming.
Source: ethereum.org · Security