# Interface

A contract describing behavior that implementing classes agree to provide.

## What is **Interface** in C#?

**Interface** — A contract describing behavior that implementing classes agree to provide.

```csharp
interface IPrintable
{
    string Format()
    {
        return "Ready";
    }
}

class Ticket : IPrintable
{
}
```

Level: Journeyman · [More C# terms at this level](https://www.ask-codey.com/glossary/subjects/c-sharp/journeyman)

Updated: September 27, 2026

## In other subjects

- [Interface in Java](https://www.ask-codey.com/glossary/interface)
- [Interface in OOP](https://www.ask-codey.com/glossary/interface-oop)

Source: https://www.ask-codey.com/glossary/interface-c-sharp