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Answer: A delegate is a type-safe reference to a method, which lets you pass methods as parameters and chain several together.

Delegates

Func<int, int> square = x => x * x;
Action<string> log = Console.WriteLine;
log += s => Debug.WriteLine(s);   // multicast chain
log("hello");                       // calls both

Events

class Downloader {
  public event EventHandler<int>? Progress;
  void Report(int pct) => Progress?.Invoke(this, pct);
}

var d = new Downloader();
d.Progress += (s, pct) => Console.WriteLine($"{pct}%");

In .NET, events conventionally use EventHandler or EventHandler<T> with EventArgs.

Notes

• An event can have many subscribers, and a subscriber can handle many events.

Claims

• id: C1 claim: Delegates allow methods to be passed as parameters. source: S1 evidence: "Delegates allow methods to be passed as parameters."
• id: C2 claim: Delegates can be chained together. source: S1 evidence: "Delegates can be chained together, such as calling multiple methods on a single event."
• id: C3 claim: The publisher decides when an event is raised; subscribers decide the response. source: S2 evidence: "The publisher determines when an event is raised; the subscribers determine what action is taken"
• id: C4 claim: An event can have multiple subscribers. source: S2 evidence: "An event can have multiple subscribers."
• id: C5 claim: .NET events are based on EventHandler and EventArgs. source: S2 evidence: "events are based on the EventHandler delegate and the EventArgs base class."

Sources

• [S1] Work with delegate types in C# - C#. Microsoft Learn (.NET docs). https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/delegates/ . License: CC BY 4.0 (dotnet/docs). Accessed 2026-11-04.
• [S2] Events - C#. Microsoft Learn (.NET docs). https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/events/ . License: CC BY 4.0 (dotnet/docs). Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_hmexbda2,
  author = {{iinventedlight}},
  title = {{C\# delegates and events}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/csharp-delegates-events/},
  note = {Permanent ID iil:note:hmexbda2. License: CC-BY-4.0.},
}

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