The string Type in Solidity: UTF-8 Text on Chain

string public name = "MudassirCoin";
string public symbol = "MUDK";
string public baseURI = "ipfs://QmXyz.../";

function setName(string calldata newName) external {
    name = newName;
}

A string declared at contract level lives in storage. A string parameter to an external function lives in calldata (cheapest), and a string used inside a function lives in memory. Choosing the right location is one of the first gas optimisations a beginner learns. The full Solidity guide covers data locations end-to-end.

The first 31 bytes of a string can fit alongside the length in a single slot. Anything longer is laid out at a separate location computed from keccak256(slot), chained 32 bytes at a time. A 200-character description costs roughly seven storage writes — at a typical 20 000 gas per fresh slot that is 140 000 gas just for the text.

string memory greeting = "Hello, smart contracts!";

// Length — count of bytes (NOT characters when there are non-ASCII chars)
uint256 byteCount = bytes(greeting).length;     // 23

// Equality — compare hashes, never == or !=
bool same = keccak256(bytes(greeting)) == keccak256(bytes("Hello, smart contracts!"));

// Concatenation — string.concat in 0.8.12+
string memory full = string.concat("Hi ", "there!");

// Char-by-char access — read the underlying bytes
bytes1 firstByte = bytes(greeting)[0];          // 0x48 ('H')

Notice how every operation goes through bytes(...). That is the only legal way to inspect a string's contents. Higher-level operations such as substring extraction, case conversion, or regex matching do not exist; libraries like OpenZeppelin's Strings fill some of the gaps but stay deliberately small because every byte processed costs gas.

// 1. ERC20 metadata
string public name;        // shown by wallets like MetaMask
string public symbol;      // 3-5 character ticker

// 2. ERC721 base URI
string public baseTokenURI;

function tokenURI(uint256 id) external view returns (string memory) {
    return string.concat(baseTokenURI, Strings.toString(id), ".json");
}

// 3. Revert reason
function withdraw(uint256 amount) external {
    require(balances[msg.sender] >= amount, "insufficient balance");
    // ...
}

// 4. ANTI-PATTERN — long descriptive text on chain
string public description = "This collection celebrates ..."; // 4 KB+ — DON'T

The first three are short, well-defined, and read by tooling. The fourth is the trap: long marketing copy belongs in an IPFS document referenced by tokenURI, not in contract storage.

For raw binary data — selectors, hashes, signatures — see the bytes type in Solidity. For names and identifiers stored in lookups, pair this with mapping in Solidity. For event payloads that include text, read events in Solidity. And for the bigger picture, the Solidity smart contracts beginner guide puts the string type in context.