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.
Fungible tokens are used for currencies, stablecoins, utility tokens, governance tokens, loyalty points, in-game currencies, and anything where the quantity matters more than the individual unit.
What makes something non-fungible
Non-fungible means unique. Each token is different from every other token, even if they come from the same collection. If I have NFT #42 from a collection and you have NFT #87, those are not interchangeable. They might have different images, different properties, different rarity, or different utility.
Think of it like event tickets. Two tickets to the same concert are not the same if one is front row and the other is in the back. They came from the same event, but each one is distinct.
Non-fungible tokens are used for digital art, collectibles, membership passes, certifications, domain names, gaming items, real estate deeds, event tickets, and anything where the individual item matters more than the quantity.
How Solana handles both with the same system
This is where Solana does something interesting. On some blockchains, fungible and non-fungible tokens are completely separate systems with different standards and different smart contracts. On Solana, both run through the same Token Program (or the newer Token Extensions program, also called Token-2022).
The difference comes down to two configuration settings: decimals and supply.
- A fungible token has a mint initialized with multiple decimals (typically 6 or 9) and a supply far greater than one. You can mint millions of fractional units from the same mint, and they are all interchangeable.
- A non-fungible token is a mint initialized with exactly 0 decimals, where exactly one token is minted and the mint authority is then permanently revoked.
That second part is worth being precise about, because there is no "maximum supply" field you set when you create a base SPL mint. A mint has a supply value that simply increments every time you mint into it. You create the mint with 0 decimals, mint exactly one token to a token account, and then set the mint authority to None. Revoking the authority is what locks the total supply at 1 forever, guaranteeing that no more units of this specific token can ever be printed.
Same program, same mint account layout. The rules are enforced purely by how you configure the mint and what you do with the mint authority.
One nuance: at this level you have created a non-fungible token. Wallets and marketplaces do not yet recognize it as an "NFT" in the way you would see it on a marketplace. That recognition comes from the metadata and standard layer, which is what we cover next.
The role of metadata
If a non-fungible token is just a mint with a supply of one, how do you know what it actually represents? How do you attach an image, a name, or specific traits to it?
This is where metadata comes in. On-chain, a token mint is just a state account holding configuration details and balances. The metadata gives it context.
The long-standing approach is the Metaplex Token Metadata standard, which creates a separate metadata account cryptographically linked to the token mint via a Program Derived Address (PDA). This account holds the token's name, symbol, and a URI pointing to an off-chain JSON file containing the image and attributes. That JSON is typically stored on decentralized storage like Arweave or IPFS, though some projects use centralized hosting such as AWS S3.
Token Metadata is still widely used and is not deprecated. Interestingly, a large share of assets minted through it today are actually fungible tokens, since it is also the common way to give a fungible mint a name, symbol, and icon.
For new NFT projects specifically, the current recommended standard is Metaplex Core. Core uses a single-account design, storing all of an asset's data in one account instead of the separate mint, metadata, and token accounts the older model required. That cuts minting cost dramatically (on the order of 80 percent cheaper than Token Metadata) and ships with built-in features like enforced royalties and a plugin system for custom behavior. If you are starting a new NFT collection today, Core is usually where you should look first.
There is also the Token Extensions (Token-2022) path. By enabling the MetadataPointer and TokenMetadata extensions, you can store the name, symbol, and URI directly inside the mint account itself. The pointer says where the metadata lives, and the metadata extension holds the actual fields. In practice this is used most often for fungible and utility tokens, letting a stablecoin or reward token carry a native icon and tracking data without a separate metadata account or any cross-program coordination at creation.
So the honest map of the landscape is: Token Metadata (legacy, still common, heavily used for fungibles), Core (the modern recommendation for new NFTs), Token-2022 metadata extensions (great for fungible and utility tokens), and compressed NFTs for high-volume cases, which we will get to in a moment.
For fungible tokens, metadata is simple. You usually just need a name, symbol, and maybe an icon. For non-fungible tokens, metadata can be extensive because each token is unique and needs its own description, image, and properties.
Token accounts work the same way
Whether you are holding a fungible token or a non-fungible one, you need a token account for it. This is the same concept you learned in the challenges. Your wallet needs an Associated Token Account (ATA) for each mint you want to hold.
For fungible tokens, your token account has a balance that can go up and down as you send and receive tokens. For non-fungible tokens, your token account has a balance of exactly one. You either have it or you do not.
The mechanics are identical. Creating the account, paying rent, transferring tokens. The same code patterns you have been writing in the challenges apply to both. (Metaplex Core is the one exception worth noting, since its single-account model does not use a separate token account in the same way, but the fungible side and classic NFTs both follow the familiar ATA pattern.)
Editions, collections, and scale
Not every NFT is a complete one-of-one. Sometimes you want to create multiple copies of the same item but still have each one be individually trackable. Think limited edition prints. There are 500 of them, each one is numbered, but they all share the same artwork.
In the Token Metadata standard, this is handled through editions. A master edition can produce a set number of prints. Each print is its own mint with its own token, but they are all linked back to the original master edition.
Collections group related NFTs together. A collection is itself an NFT that acts as a parent. Individual NFTs reference the collection in their metadata, which is how marketplaces know that 10,000 different mints all belong to the same project.
Here is an important practical point that trips people up. Editions and one-mint-per-item NFTs do not scale cheaply. Each one is a real account that carries rent. So if your goal is something like 1,000 identical-but-individually-owned event tickets, minting a thousand separate full NFTs gets expensive fast.
For that high-volume case, the modern answer is compressed NFTs (the Metaplex Bubblegum standard). Compressed NFTs store ownership data in a Merkle tree rather than in a full account per token, which makes it possible to mint thousands or even millions of individually owned, transferable assets at a tiny fraction of the cost. This is the dominant approach for large drops on Solana today, and it is exactly what you would reach for in the 1,000-ticket scenario.
So the decision for "many of the same thing" is really: a handful of numbered prints can use editions, but anything at real scale should use compression.
Fungible tokens with NFT properties
The Token Extensions program blurs the traditional line between fungible and non-fungible tokens in powerful ways:
- Non-Transferable Tokens: By initializing a fungible mint with the NonTransferable extension, you create assets that are locked to the recipient's wallet the moment they are minted. If a user earns 50 reputation points, those points are structurally fungible but behave like "soulbound" credentials because the runtime blocks any transfer instruction.
- Mint-Linked Metadata: Before Token Extensions, detailed metadata was largely reserved for NFTs via Metaplex. Now, you can inject rich metadata directly into a fungible utility token or stablecoin mint, allowing wallets to display custom icons and tracking data natively.
- Transfer Hooks: You can attach a custom program to a fungible token mint that executes additional logic every time a transfer occurs. A fungible token that checks an allowlist or verifies a KYC credential before allowing a transfer begins to behave like a restricted real-world security, changing its economic behavior entirely through code.
The categories are not as rigid as they seem. Solana gives you the building blocks and you decide how to combine them.
When to use which
If you are building something where every unit is the same and users care about quantity, use a fungible token. Currencies, points, credits, governance votes.
If you are building something where each item is unique and users care about the specific item they hold, use a non-fungible token. Art, collectibles, certificates, tickets, identity documents. For a brand-new collection, start with Metaplex Core. For high-volume drops, reach for compressed NFTs.
If you are building something in between, like a limited-edition with 100 copies or a membership tier with different levels, look at editions and collections, or explore how Token-2022 extensions can give you the behavior you need.
The good news is that the skills you are building in these challenges apply to all of it. The mint, token account, and transfer patterns are the same regardless of whether you are working with fungible or non-fungible tokens.
What is coming next
The upcoming challenges will take you deeper into how NFTs work on Solana, how to mint them, how metadata is structured, and how collections come together. Understanding the foundation covered here will make those challenges click faster.
Keep building. See you in the Discord.
100 Days of Solana is a free daily coding challenge: https://mlh.link/solana-100
