If you have been following the 100 Days of Solana challenges, you have already worked with tokens. You created mints, set up token accounts, transferred SOL, and explored token extensions. But there is a distinction that comes up constantly in web3, and understanding it properly will change how you think about everything you build going forward.
Fungible and non-fungible tokens. You have probably heard these terms before, especially NFTs. But what do they actually mean on Solana, and how does the same token system handle two very different concepts?
What makes something fungible
Fungible just means interchangeable. One unit is identical to another unit. If I have 10 USDC and you have 10 USDC, ours are exactly the same. It does not matter which specific USDC tokens I hold because they are all worth the same and behave the same way. We could swap them and nothing changes.
This is how most things you are used to work. A dollar bill is fungible. A liter of petrol is fungible. One unit of SOL is the same as any other unit of SOL. When you built token transfers in the challenges, you were working with fungible tokens. You did not need to care about which specific tokens moved, just how many.
