# base

*noun*

say it: **“BAYS”** **/beɪs/**

The C# keyword a derived class uses to reach its base class, to call its constructor or its version of a method.

## What is **base** in C#?

**base** — The keyword a derived class uses to reach its base class. `: base(...)` after a constructor passes values up to the base constructor, and `base.Method()` runs the base class's version of a method you've overridden.

```csharp
class Ebook : Book
{
    public Ebook(string title, int fileSizeMb) : base(title)
    {
        FileSizeMb = fileSizeMb;
    }
    public int FileSizeMb { get; }
}
```

## In a sentence

- “The Ebook constructor passes the title up with : **base**(title).”

Level: Journeyman · [More C# terms at this level](https://www.ask-codey.com/glossary?category=c-sharp&level=3)

Updated: October 28, 2026

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