Understanding Solana NFTs: A Complete Guide

This document explains everything you see when viewing an NFT on Solana Explorer, how each piece was created, and what can be changed after minting.

The Big Picture
Accounts Created When Minting
On-Chain vs Off-Chain Data
Explorer Fields Explained
What Can Be Changed
How to Update NFT Data
Collection Verification
Cost Breakdown

The Big Picture

A Solana NFT is not a single piece of data. It’s a system of connected accounts that together represent ownership and metadata of a unique digital asset.

┌─────────────────────────────────────────────────────────────────┐
│                        SOLANA BLOCKCHAIN                         │
├─────────────────────────────────────────────────────────────────┤
│                                                                  │
│  ┌──────────────┐    ┌──────────────┐    ┌──────────────┐       │
│  │  Mint        │    │  Metadata    │    │  Master      │       │
│  │  Account     │───▶│  Account     │───▶│  Edition     │       │
│  │              │    │  (PDA)       │    │  (PDA)       │       │
│  └──────────────┘    └──────────────┘    └──────────────┘       │
│         │                   │                                    │
│         │                   │ points to                          │
│         ▼                   ▼                                    │
│  ┌──────────────┐    ┌──────────────────────────────────┐       │
│  │  Token       │    │  OFF-CHAIN (Arweave/IPFS)        │       │
│  │  Account     │    │  ┌────────────────────────────┐  │       │
│  │  (holds 1)   │    │  │  metadata.json             │  │       │
│  └──────────────┘    │  │  - name, description       │  │       │
│         │            │  │  - image URL               │  │       │
│         │ owned by   │  │  - attributes              │  │       │
│         ▼            │  └────────────────────────────┘  │       │
│  ┌──────────────┐    │  ┌────────────────────────────┐  │       │
│  │  Your        │    │  │  image.png                 │  │       │
│  │  Wallet      │    │  │  (the actual artwork)      │  │       │
│  └──────────────┘    │  └────────────────────────────┘  │       │
│                      └──────────────────────────────────┘       │
│                                                                  │
└─────────────────────────────────────────────────────────────────┘

Key Insight: The blockchain stores ownership and pointers. The actual image and rich metadata live off-chain on permanent storage (Arweave via Irys).

Accounts Created When Minting

When you run mint-nft.ts, four accounts are created:

1. Mint Account

What it is: The unique identifier for your NFT. This address IS your NFT.

Created by: createNft() function in our script

const nftMint = generateSigner(umi);
// This generates a new keypair - the public key becomes the mint address

On Explorer: This is the main address you see (e.g., 4ZsKxVKmCFZx1xcRamFkwTLrRW6gMzfkVqLUGcfobmJ5)

Contains:

Field	Value	Meaning
Supply	1	Only 1 token exists (NFT = non-fungible)
Decimals	0	Cannot be divided (unlike SOL with 9 decimals)
Mint Authority	null	No one can mint more (frozen after creation)
Freeze Authority	null	No one can freeze the token

Why Mint Authority is null: For a true NFT, we set supply = 1 and then remove the mint authority so no more can ever be created. This happens automatically with createNft().

2. Token Account (Associated Token Account)

What it is: Holds the actual token. Think of it as a “wallet slot” for this specific NFT.

Created by: Automatically created by createNft() for the recipient

Address: Derived deterministically from (owner wallet + mint address)

Token Account = PDA(owner_wallet, TOKEN_PROGRAM, mint_address)

On Explorer: Shows under “Token Accounts” or “Holders”

Contains:

Field	Value	Meaning
Mint	NFT mint address	Which token type this holds
Owner	Recipient wallet	Who owns this token account
Amount	1	How many tokens (always 1 for NFT)

Key Concept: You don’t “own” the mint. You own a token account that holds 1 unit of that mint.

3. Metadata Account (PDA)

What it is: Stores NFT metadata on-chain. This is where the name, symbol, and URI live.

Created by: Metaplex Token Metadata Program via createNft()

Address: A Program Derived Address (PDA) - deterministically calculated:

// How Metaplex finds the metadata account
const metadataPda = findMetadataPda(umi, { mint: nftMint.publicKey });
// PDA = seeds("metadata", TOKEN_METADATA_PROGRAM, mint_address)

On Explorer: Click “Metadata” tab on the NFT page

Contains:

Field	Our Value	Meaning
Name	”Founder #1”	Display name (max 32 chars on-chain)
Symbol	”TREE”	Collection symbol (max 10 chars)
URI	`https://arweave.net/...`	Points to off-chain JSON
Seller Fee Basis Points	0	Royalty percentage (0 = 0%)
Creators	[{ address, verified, share }]	Who created this + royalty split
Collection	{ key, verified }	Which collection this belongs to
Is Mutable	true	Can metadata be updated?
Update Authority	Your wallet	Who can update metadata
Primary Sale Happened	false	Has this been sold?

4. Master Edition Account (PDA)

What it is: Proves this is a “master” NFT (not a print/copy). Controls edition printing.

Created by: Automatically by createNft()

Address: Another PDA derived from the mint:

Master Edition PDA = seeds("metadata", TOKEN_METADATA_PROGRAM, mint, "edition")

Contains:

Field	Value	Meaning
Supply	0	Number of prints made from this master
Max Supply	None/0	Maximum prints allowed (None = unlimited potential)

Why it exists: Metaplex supports “editions” where you can print copies of a master NFT. For our utility NFTs, we don’t use this feature, but the account is still required.

On-Chain vs Off-Chain Data

On-Chain (Stored on Solana)

Stored directly in the Metadata Account:

- name (truncated to 32 chars)
- symbol (truncated to 10 chars)
- uri (pointer to off-chain JSON)
- seller_fee_basis_points
- creators array
- collection reference
- is_mutable flag
- update_authority

Cost: ~0.00561 SOL rent-exempt minimum for metadata account

Off-Chain (Stored on Arweave via Irys)

The URI points to a JSON file:

{
  "name": "Founder #1",
  "symbol": "TREE",
  "description": "TreehouseHQ Owner NFT. Grants ownership of one TreehouseHQ workspace. Founder Edition.",
  "image": "https://arweave.net/abc123...",
  "external_url": "https://treehousehq.io",
  "attributes": [
    { "trait_type": "Edition", "value": "Founder" },
    { "trait_type": "Number", "value": "1" },
    { "trait_type": "Type", "value": "Owner" }
  ],
  "properties": {
    "files": [{ "uri": "https://arweave.net/abc123...", "type": "image/png" }],
    "category": "image"
  }
}

Why off-chain?

Cost: Storing a 500KB image on-chain would cost ~3.5 SOL in rent
Flexibility: JSON can contain unlimited data
Permanence: Arweave stores data forever (pay once)

Created by: Our script’s upload step:

// Upload image first
const [imageUri] = await umi.uploader.upload([imageFile]);

// Then upload JSON that references the image
const metadataUri = await umi.uploader.uploadJson({
  name: nftName,
  image: imageUri,
  // ... other fields
});

Explorer Fields Explained

When you view 4ZsKxVKmCFZx1xcRamFkwTLrRW6gMzfkVqLUGcfobmJ5 on Solana Explorer:

Overview Tab

Field	Example	Source	Explanation
Address	4ZsKxVKm…	Mint Account	The NFT’s unique identifier
Owner Program	Token Metadata Program	-	Metaplex program that manages this
Balance	0 SOL	Mint Account	Mint accounts don’t hold SOL
Token	TREE	Metadata PDA	Symbol from metadata
Decimals	0	Mint Account	NFTs have 0 decimals
Supply	1	Mint Account	Only 1 exists

Metadata Tab

Field	Example	Mutable?	Explanation
Name	Founder #1	Yes*	Display name
Symbol	TREE	Yes*	Token symbol
URI	https://arweave.net/…	Yes*	Off-chain metadata URL
Seller Fee	0%	Yes*	Royalty on secondary sales
Update Authority	SQavJPZ…	Yes	Who can modify metadata
Is Mutable	true	One-way	Can be set to false (irreversible)
Primary Sale	false	One-way	Set true after first sale

*Only if is_mutable = true

Collection Section

Field	Example	Explanation
Collection Address	8YK7GZH…	Which collection this belongs to
Verified	Yes (checkmark)	Collection authority confirmed membership

Creators Section

Field	Example	Explanation
Address	SQavJPZ…	Creator wallet
Verified	Yes	Creator signed to confirm
Share	100%	Royalty share (if royalties enabled)

Holders Tab

Shows the Token Account:

Field	Example	Explanation
Owner	SQavJPZ…	Wallet that owns the NFT
Token Account	7xYz…	ATA holding the token
Amount	1	Always 1 for NFTs

What Can Be Changed

Always Changeable (if mutable)

Field	How to Change	Notes
Name	Update metadata	Max 32 chars on-chain
Symbol	Update metadata	Max 10 chars
URI	Update metadata	Point to new JSON
Image	Upload new, update URI	Old image stays on Arweave
Attributes	Upload new JSON, update URI
Description	Upload new JSON, update URI
Seller Fee	Update metadata	0-10000 basis points
Creators	Update metadata	Complex rules apply
Update Authority	Transfer authority	Can delegate to another wallet

One-Way Changes (cannot undo)

Field	Change	Effect
Is Mutable	true → false	Freezes all metadata forever
Primary Sale	false → true	Indicates first sale happened
Collection Verified	false → true	Only collection authority can do this

Never Changeable

Field	Why
Mint Address	It’s the account’s public key
Mint Authority	Set to null on creation
Supply	Frozen at 1
Decimals	Set at creation, immutable
Master Edition	Created once

How to Update NFT Data

Update On-Chain Metadata

Create a new script scripts/update-metadata.ts:

import { createUmi } from '@metaplex-foundation/umi-bundle-defaults';
import {
  mplTokenMetadata,
  updateV1,
  findMetadataPda,
} from '@metaplex-foundation/mpl-token-metadata';
import { keypairIdentity, publicKey } from '@metaplex-foundation/umi';

async function updateNftMetadata() {
  const umi = createUmi('https://api.devnet.solana.com')
    .use(mplTokenMetadata());

  // Load your keypair (must be update authority)
  const keypair = umi.eddsa.createKeypairFromSecretKey(secretKey);
  umi.use(keypairIdentity(keypair));

  const mintAddress = publicKey('4ZsKxVKmCFZx1xcRamFkwTLrRW6gMzfkVqLUGcfobmJ5');

  await updateV1(umi, {
    mint: mintAddress,
    data: {
      name: 'New Name Here',
      symbol: 'TREE',
      uri: 'https://arweave.net/new-metadata-uri',
      sellerFeeBasisPoints: 0,
      creators: null, // keep existing
    },
  }).sendAndConfirm(umi);

  console.log('Metadata updated!');
}

Update Off-Chain Data (Image/Attributes)

You cannot modify files on Arweave. Instead:

Upload new files to get new URIs
Update on-chain URI to point to new JSON

// 1. Upload new image
const newImageBuffer = fs.readFileSync('assets/new-image.png');
const [newImageUri] = await umi.uploader.upload([{
  buffer: newImageBuffer,
  fileName: 'new-image.png',
  contentType: 'image/png',
}]);

// 2. Upload new metadata JSON
const newMetadataUri = await umi.uploader.uploadJson({
  name: 'Updated NFT Name',
  image: newImageUri,
  attributes: [
    { trait_type: 'Edition', value: 'Founder' },
    { trait_type: 'Upgraded', value: 'true' },
  ],
});

// 3. Update on-chain URI
await updateV1(umi, {
  mint: mintAddress,
  data: {
    name: 'Updated NFT Name',
    uri: newMetadataUri,
    // ... other fields
  },
}).sendAndConfirm(umi);

Transfer Update Authority

To let someone else update the NFT:

import { updateV1 } from '@metaplex-foundation/mpl-token-metadata';

await updateV1(umi, {
  mint: mintAddress,
  newUpdateAuthority: publicKey('NEW_AUTHORITY_WALLET'),
}).sendAndConfirm(umi);

Make NFT Immutable (Permanent)

Warning: This cannot be undone!

await updateV1(umi, {
  mint: mintAddress,
  isMutable: false,
}).sendAndConfirm(umi);

After this, no one can ever change the metadata again.

Collection Verification

Why Verification Matters

Anyone can create an NFT and claim it belongs to a collection. Verification proves the collection authority approved this NFT’s membership.

Unverified: NFT says "I'm in TreehouseHQ collection" (anyone can claim)
Verified:   Collection authority signed "Yes, this NFT is in my collection"

How We Verify

In our mint script:

// 1. Create NFT with collection reference (unverified)
await createNft(umi, {
  // ...
  collection: {
    key: publicKey(collectionAddress),
    verified: false,  // Initially unverified
  },
}).sendAndConfirm(umi);

// 2. Collection authority verifies it
await verifyCollectionV1(umi, {
  metadata: findMetadataPda(umi, { mint: nftMint.publicKey }),
  collectionMint: publicKey(collectionAddress),
  authority: umi.identity,  // Must be collection update authority
}).sendAndConfirm(umi);

Unverify (Remove from Collection)

import { unverifyCollectionV1 } from '@metaplex-foundation/mpl-token-metadata';

await unverifyCollectionV1(umi, {
  metadata: findMetadataPda(umi, { mint: nftMint.publicKey }),
  collectionMint: publicKey(collectionAddress),
  authority: umi.identity,
}).sendAndConfirm(umi);

Cost Breakdown

One-Time Costs (rent-exempt deposits)

These are not “spent” - they’re held as rent deposits and could theoretically be recovered if accounts are closed:

Account	Size (bytes)	Rent (SOL)
Mint Account	82	~0.00144
Metadata Account	679	~0.00561
Master Edition	282	~0.00277
Token Account	165	~0.00203
Total per NFT		~0.0118 SOL

Transaction Fees

Operation	Fee (SOL)
Create NFT	~0.000005
Verify Collection	~0.000005
Update Metadata	~0.000005

Storage Costs (Arweave via Irys)

Item	Typical Size	Cost
Image (500KB)	500,000 bytes	~0.002 SOL
Metadata JSON	~1KB	~0.00001 SOL

Total Cost per NFT

Rent deposits:     ~0.012 SOL
Transaction fees:  ~0.00001 SOL
Storage (image):   ~0.002 SOL
Storage (JSON):    ~0.00001 SOL
─────────────────────────────
Total:             ~0.014 SOL (~$2-3 at typical prices)

Glossary

Term	Definition
Mint	The token type definition. For NFTs, supply = 1.
PDA	Program Derived Address. Deterministically calculated, no private key.
ATA	Associated Token Account. Standard token account for a wallet.
Rent	SOL deposit required to keep an account alive on Solana.
Rent-Exempt	Account has enough SOL to live forever (minimum balance).
Basis Points	1/100th of a percent. 100 bp = 1%, 10000 bp = 100%.
URI	Uniform Resource Identifier. Link to off-chain data.
Arweave	Permanent decentralized storage network.
Irys	Service that pays Arweave fees using SOL (formerly Bundlr).
Update Authority	Wallet that can modify NFT metadata.
Collection Authority	Wallet that can verify/unverify collection membership.

Your NFT Summary

Based on our devnet test:

Mint Address:        4ZsKxVKmCFZx1xcRamFkwTLrRW6gMzfkVqLUGcfobmJ5
Owner:               SQavJPZYN5s5iW72Q5e652oZC9nmSwcwZgeBms15j61
Collection:          8YK7GZHykNvHKeGC7dnqC6LPVrtMDGy3Jam9h6Fhj78V
Name:                Founder #1
Symbol:              TREE
Is Mutable:          true (can update artwork later)
Royalties:           0%
Collection Verified: Yes
Network:             Devnet

What you can change:

Name, symbol, description
Image (upload new, update URI)
Attributes
Update authority (transfer to another wallet)

What you cannot change:

Mint address
That it’s an NFT (supply = 1)
History of ownership (stored in transactions)