Crypto in fifteen minutes: wallet, network, token, USDC

Why you need this at all

Polymarket has no bank accounts or cards in the usual sense. The balance is held in the crypto dollar USDC and trades are recorded on the Polygon blockchain. To deposit and to withdraw winnings you need five concepts. It is no harder than online banking; the words are just new.

1. Blockchain and network

A blockchain is a shared ledger of who holds what. Nobody stores it in one place, so it cannot be forged and entries cannot be undone. There are many networks: Ethereum, Polygon, Tron, Solana and others. They are separate ledgers, not directly connected. Polymarket runs on Polygon. Remember the word: you will pick it from a list on every transfer.

2. Token and USDC

A token is a record of an asset inside a network. Bitcoin is the token of the Bitcoin network, ether of Ethereum. USDC is a token that the company Circle issues at exactly 1 USDC = 1 dollar, holding dollars in reserve. Such tokens are called stablecoins. USDT from Tether is similar. Polymarket's balance is in USDC; USDT deposits are accepted and converted.

The same USDC exists on several networks. USDC on Polygon and USDC on Ethereum are different records. Sending a token from one network to an address on another without a bridge does not work: the money gets stuck or lost. That is the mistake that costs real money.

3. Address

An address is your account number on a network, a long string like 0x3a9f…c21e. You can show it to anyone; an address can only receive. Ethereum and Polygon addresses look identical and start with 0x, but a token sent on Ethereum will not appear on Polygon. The network is chosen separately from the address.

4. Wallet and seed phrase

A wallet is a program that holds your secret key and signs transfers with it: a browser extension or a phone app. On creation it shows a seed phrase, 12 or 24 words. That phrase is the key to all funds on all addresses of the wallet. Whoever knows it owns the money; there are no passwords and no email recovery.

Non-negotiable rules: write it on paper, keep it in two places, never photograph it, never type it into any website, never share it. Anyone asking for your seed phrase "for support" or "verification" is a scammer, no exceptions.

5. Network fee

Every blockchain entry costs a fee paid to those who run the network. On Ethereum a transfer can cost dollars; on Polygon a fraction of a cent. The fee is paid in the network's native coin: on Polygon that is POL (formerly MATIC). To send USDC from your own wallet on Polygon you need a little POL on the same address; one dollar's worth covers hundreds of transfers. Polymarket handles this internally, but when you withdraw to your own wallet and onward to an exchange you will need POL for the fee.

Exchange versus wallet

There are two places your tokens can live. An exchange is a company: you get an account with a login and password, it keeps the keys for you, but it requires ID and can freeze an account. Your own wallet is your keys: nobody can freeze it, and nobody can help if you lose the phrase. The usual flow: buy USDC on an exchange with ordinary money, then withdraw it to your wallet or directly to your Polymarket deposit address.

Check yourself

• Which network does Polymarket use? Polygon.
• What happens if you send USDC on Ethereum to a Polygon deposit address? It will not reach the balance; at best a manual recovery, at worst a loss.
• Who may know your seed phrase? Nobody.
• What pays the transfer fee on Polygon? POL on the same address.

Next: installing a wallet and saving the seed phrase properly.