# What is blockchain and cryptocurrency

Understanding blockchain and cryptocurrency helps you understand why STON.fi works without accounts, passwords, or intermediaries, and why your wallet is the key to everything.

### What is a blockchain?

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A **blockchain** is a shared digital ledger: think of it as a public spreadsheet that anyone can read, but no one can secretly edit.
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Instead of being stored on a single server, this ledger is distributed across thousands of computers around the world. Each new update is grouped into a “block,” and blocks are linked together in a strict order, forming a chain — hence the name blockchain.

On the TON blockchain, new blocks are produced roughly every few seconds, continuously extending this shared history.

### Why blockchains are hard to change

Each block contains a fingerprint (called a hash) of the previous block. If someone tried to alter past data, this fingerprint would break, and the entire chain after it would no longer match.

To successfully rewrite history, an attacker would need to redo the work for every block after it, faster than the rest of the network combined. In practice, this makes blockchains extremely resistant to tampering.

For users, this means:

* Transactions are transparent
* Records are permanent
* Trust comes from math and network consensus, not from a single company or person

### What is cryptocurrency

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**Cryptocurrency** is a digital asset that exists on a blockchain.
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There are no banks involved in holding or moving crypto. Ownership is defined by cryptographic keys, and transactions are recorded directly on the blockchain’s public ledger.

When you send or receive cryptocurrency, you’re not moving coins between accounts. You’re updating the blockchain’s shared record to reflect a new owner.

### Coins vs tokens

These terms are often mixed, but here’s a way to think about them:

* **Coins** — native assets of a blockchain.\
  Example: TON on the TON blockchain.
* **Tokens** — assets created on top of a blockchain via smart contracts.\
  Example: USDt, STON, and other jettons on TON.

On STON.fi, you mostly interact with tokens, and you need to hold a bit of TON: it is used to pay network fees and power transactions.

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STON.fi is a DeFi protocol built on TON. It doesn’t hold your funds or manage balances internally. Instead:

* Your wallet signs transactions
* Smart contracts execute swaps and liquidity operations
* The blockchain records everything transparently
  {% endhint %}

In the next guides, we’ll explore how this foundation turns into real actions: wallets, swaps, liquidity pools, farming, and staking.

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