# Source: https://docs.datadoghq.com/security/code_security/static_analysis/static_analysis_rules/csharp-code-style/interface-first-letter.md

---
title: Interface names should start with I
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Datadog Security > Code Security > Static Code Analysis (SAST) > SAST
  Rules > Interface names should start with I
---

# Interface names should start with I

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## Metadata{% #metadata %}

**ID:** `csharp-code-style/interface-first-letter`

**Language:** C#

**Severity:** Notice

**Category:** Code Style

## Description{% #description %}

The first letter of an interface should be `I`.

#### Learn More{% #learn-more %}

- [C# Google Style Guide](https://google.github.io/styleguide/csharp-style.html)

## Non-Compliant Code Examples{% #non-compliant-code-examples %}

```csharp
interface Service {
    void myMethod();
}
```

## Compliant Code Examples{% #compliant-code-examples %}

```csharp
interface IService {
    void myMethod();
}
```
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