What is the difference between delegate and event in C#? [duplicate]

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What is the difference between a delegate and events?

This question I got at an interview and I still don't know what the answer should be.
I would appreciate any thoughts!

Answer 1

I have an article on pretty much exactly

In brief, you can think of an event as being a bit like a property - but instead of having get/set operations, it has add/remove. The value being added/removed is always a delegate reference.

Delegates themselves support operations of:

• Combine (chain multiple delegate instances together)
• Remove (split them up again)
• Invoke (synchronous or asynchronous)
• Various things to do with finding out the target, invocation list etc

Note that delegates themselves are immutable, so combine/remove operations return a new delegate instance rather than modifying the existing ones.

Answer 2

The other answers so far are all quite good. Here's another way to think about it.

What's the semantic difference between a property and a field? I don't mean what are the technical differences, like a property is actually a pair of methods, blah blah blah. I mean, as far as understanding the meaning of a program goes, what is the difference?

A property is usually a public member of a class, and it represents a property of the thing being modelled. That is, you want to make a model of a newspaper so you make a class Newspaper and you give it a property Publisher. The publisher is a property of newspapers, so Publisher is a property of the Newspaper class.

A field is usually an implementation detail of a class. Maybe the Publisher property is actually implemented as a field. But newspapers do not have "fields", so you don't expose the publisher field as a public member of the Newspaper class; you use it as a private implementation detail of the Publisher property.

Events and delegates are somewhat analogous. An event is something in the model. A button is a thing that can inform you when it is clicked, so the Button class has a "Click" event. The delegate that actually does the informing is the implementation detail of the event.