Answer
string is immutable, while StringBuilder maintains a mutable character buffer. • Changing a string expression creates a new string result. • StringBuilder can reduce temporary allocations during many incremental modifications. • For a small fixed number of concatenations, normal string operations are often clearer.
💡 C# Example
var builder = new System.Text.StringBuilder();
builder.Append("Hello");
builder.Append(' ');
builder.Append("C#");
Console.WriteLine(builder.ToString());
Output
Hello C#
⚡ Quick Revision
Use string for immutable text and StringBuilder for repeated edits.