---
title: "What is the difference between string and StringBuilder?"  
description: "What is the difference between string and StringBuilder?"  
author: "ICSM Computer"  
published: 2025-07-01  
updated: 2026-06-05  
canonical: https://www.mindstick.com/forum/161763/what-is-the-difference-between-string-and-stringbuilder  
category: "c#"  
tags: ["c#"]  
reading_time: 1 minute  

---

# What is the difference between string and StringBuilder?

What is the [difference](https://www.mindstick.com/articles/157114/good-news-or-bad-news-and-the-difference-is) between `string` and `StringBuilder`?

## Replies

### Reply by ICSM Computer

### String vs StringBuilder in C#

| String | StringBuilder |
| --- | --- |
| **Immutable** (cannot be changed after creation) | **Mutable** (can be modified) |
| Every change creates a **new string object** | Changes occur in the **same buffer/object** |
| Slower for repeated concatenation in loops | Faster for frequent append/insert/remove operations |
| Suitable for fixed or rarely changing text | Suitable for dynamically changing text |
| Defined in `System.String` | Defined in `System.Text.StringBuilder` |

## Example:

```cs
// String
string str = "Hello";
str += " World";   // Creates a new string object

// StringBuilder
StringBuilder sb = new StringBuilder("Hello");
sb.Append(" World");   // Modifies existing buffer
```

## Interview answer (short):

> `string` is immutable, meaning any modification creates a new object. `StringBuilder` is mutable, allowing text to be modified without creating new objects repeatedly, making it more efficient for frequent string manipulations.


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Original Source: https://www.mindstick.com/forum/161763/what-is-the-difference-between-string-and-stringbuilder

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