# 2. Basic Syntax

# import namespace

## Global import

C# >=10 support global keyword. If import namespace with global keyword, that namespace can available over all .cs file.

```csharp
# GlobalUsings.cs
global using System;
```

It can be done by adding `ImplicitUsings` attribute on the `.csproj` file. This attribute will add frequently used namespace such as `System`. Also, adding `Using` attribute inside of `ItemGroup` on `.csproj` does the same thing as `global` keyword.

```plaintext
<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net7.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <Using Include="System" />
  </ItemGroup>

</Project>
```

If `ImplicitUsing` attribute is enabled, SDK automatically generate &lt;ProjectName&gt;.GlobalUsings.g.cs under /obj/debug/net7.0.

This file looks like this.

```csharp
// <auto-generated/>
global using global::System;
global using global::System.Collections.Generic;
global using global::System.IO;
global using global::System.Linq;
global using global::System.Net.Http;
global using global::System.Threading;
global using global::System.Threading.Tasks;
```

## Reference

[MS Dev blog - Explanation about import statement is good](https://devblogs.microsoft.com/dotnet/welcome-to-csharp-10/)