Sure! Here is the SEO-friendly HTML answer for the interview question "What is the difference between String and StringBuilder in C#?" with the focus keyword identified and included:

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The Difference Between String and StringBuilder in C#

In C#, the main difference between String and StringBuilder is their immutability. Strings in C# are immutable, meaning that any operation that appears to modify a string actually creates a new string instance in memory. On the other hand, StringBuilder is mutable and allows for efficient manipulation of the string data without creating new instances.

When concatenating or modifying strings frequently, using StringBuilder can be more efficient in terms of memory and performance compared to using regular String objects.

It's important to choose between String and StringBuilder based on the requirements of your application to ensure optimal performance and memory usage.

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