diff --git a/Directory.Build.props b/Directory.Build.props
index f01572a..3c59a5b 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -5,7 +5,7 @@
 		<LangVersion>12.0</LangVersion>
 		
 		<!-- NuGet -->
-		<Version>2.0.13</Version>
+		<Version>2.0.14</Version>
 		<AssemblyVersion>2.0.0</AssemblyVersion>
 		<FileVersion>2.0.0</FileVersion>
 		<Authors>Jon Sagara</Authors>
diff --git a/src/Sagara.Core/Extensions/IEnumerableExtensions.cs b/src/Sagara.Core/Extensions/IEnumerableExtensions.cs
new file mode 100644
index 0000000..9e74fa8
--- /dev/null
+++ b/src/Sagara.Core/Extensions/IEnumerableExtensions.cs
@@ -0,0 +1,21 @@
+namespace Sagara.Core;
+
+public static class IEnumerableExtensions
+{
+#if NET6_0 || NET7_0 || NET8_0
+    /// <summary>
+    /// Returns an enumerable that incorporates the element's index into a tuple.
+    /// </summary>
+    /// <remarks>
+    /// NOTE: This will be built into .NET 9 and above, so this method is for .NET 8 and below.
+    /// </remarks>
+    /// <typeparam name="TSource">The type of the elements of <paramref name="source" />.</typeparam>
+    /// <param name="source">The source enumerable providing the elements.</param>
+    public static IEnumerable<(int Index, TSource Item)> Index<TSource>(this IEnumerable<TSource> source)
+    {
+        ArgumentNullException.ThrowIfNull(source);
+
+        return source.Select((item, index) => (index, item));
+    }
+#endif
+}
diff --git a/src/Sagara.Core/docs/Sagara.Core.IEnumerableExtensions.md b/src/Sagara.Core/docs/Sagara.Core.IEnumerableExtensions.md
new file mode 100644
index 0000000..b782d25
--- /dev/null
+++ b/src/Sagara.Core/docs/Sagara.Core.IEnumerableExtensions.md
@@ -0,0 +1,41 @@
+#### [Sagara.Core](index.md 'index')
+### [Sagara.Core](index.md#Sagara.Core 'Sagara.Core')
+
+## IEnumerableExtensions Class
+
+```csharp
+public static class IEnumerableExtensions
+```
+
+Inheritance [System.Object](https://docs.microsoft.com/en-us/dotnet/api/System.Object 'System.Object') &#129106; IEnumerableExtensions
+### Methods
+
+<a name='Sagara.Core.IEnumerableExtensions.Index_TSource_(thisSystem.Collections.Generic.IEnumerable_TSource_)'></a>
+
+## IEnumerableExtensions.Index<TSource>(this IEnumerable<TSource>) Method
+
+Returns an enumerable that incorporates the element's index into a tuple.
+
+```csharp
+public static System.Collections.Generic.IEnumerable<(int Index,TSource Item)> Index<TSource>(this System.Collections.Generic.IEnumerable<TSource> source);
+```
+#### Type parameters
+
+<a name='Sagara.Core.IEnumerableExtensions.Index_TSource_(thisSystem.Collections.Generic.IEnumerable_TSource_).TSource'></a>
+
+`TSource`
+
+The type of the elements of [source](Sagara.Core.IEnumerableExtensions.md#Sagara.Core.IEnumerableExtensions.Index_TSource_(thisSystem.Collections.Generic.IEnumerable_TSource_).source 'Sagara.Core.IEnumerableExtensions.Index<TSource>(this System.Collections.Generic.IEnumerable<TSource>).source').
+#### Parameters
+
+<a name='Sagara.Core.IEnumerableExtensions.Index_TSource_(thisSystem.Collections.Generic.IEnumerable_TSource_).source'></a>
+
+`source` [System.Collections.Generic.IEnumerable&lt;](https://docs.microsoft.com/en-us/dotnet/api/System.Collections.Generic.IEnumerable-1 'System.Collections.Generic.IEnumerable`1')[TSource](Sagara.Core.IEnumerableExtensions.md#Sagara.Core.IEnumerableExtensions.Index_TSource_(thisSystem.Collections.Generic.IEnumerable_TSource_).TSource 'Sagara.Core.IEnumerableExtensions.Index<TSource>(this System.Collections.Generic.IEnumerable<TSource>).TSource')[&gt;](https://docs.microsoft.com/en-us/dotnet/api/System.Collections.Generic.IEnumerable-1 'System.Collections.Generic.IEnumerable`1')
+
+The source enumerable providing the elements.
+
+#### Returns
+[System.Collections.Generic.IEnumerable&lt;](https://docs.microsoft.com/en-us/dotnet/api/System.Collections.Generic.IEnumerable-1 'System.Collections.Generic.IEnumerable`1')[&lt;](https://docs.microsoft.com/en-us/dotnet/api/System.ValueTuple 'System.ValueTuple')[System.Int32](https://docs.microsoft.com/en-us/dotnet/api/System.Int32 'System.Int32')[,](https://docs.microsoft.com/en-us/dotnet/api/System.ValueTuple 'System.ValueTuple')[TSource](Sagara.Core.IEnumerableExtensions.md#Sagara.Core.IEnumerableExtensions.Index_TSource_(thisSystem.Collections.Generic.IEnumerable_TSource_).TSource 'Sagara.Core.IEnumerableExtensions.Index<TSource>(this System.Collections.Generic.IEnumerable<TSource>).TSource')[&gt;](https://docs.microsoft.com/en-us/dotnet/api/System.ValueTuple 'System.ValueTuple')[&gt;](https://docs.microsoft.com/en-us/dotnet/api/System.Collections.Generic.IEnumerable-1 'System.Collections.Generic.IEnumerable`1')
+
+### Remarks
+NOTE: This will be built into .NET 9 and above, so this method is for .NET 8 and below.
\ No newline at end of file
diff --git a/src/Sagara.Core/docs/index.md b/src/Sagara.Core/docs/index.md
index 864f254..a94dd71 100644
--- a/src/Sagara.Core/docs/index.md
+++ b/src/Sagara.Core/docs/index.md
@@ -24,6 +24,8 @@
   - **[NotNull&lt;T&gt;(T, string, string, int, string)](Sagara.Core.Check.md#Sagara.Core.Check.NotNull_T_(T,string,string,int,string) 'Sagara.Core.Check.NotNull<T>(T, string, string, int, string)')** `Method` Throws an [System.ArgumentNullException](https://docs.microsoft.com/en-us/dotnet/api/System.ArgumentNullException 'System.ArgumentNullException') if the value is null.
   - **[NotOutOfRange&lt;T&gt;(T, T, T, string, string, int, string)](Sagara.Core.Check.md#Sagara.Core.Check.NotOutOfRange_T_(T,T,T,string,string,int,string) 'Sagara.Core.Check.NotOutOfRange<T>(T, T, T, string, string, int, string)')** `Method` Throws an [System.ArgumentOutOfRangeException](https://docs.microsoft.com/en-us/dotnet/api/System.ArgumentOutOfRangeException 'System.ArgumentOutOfRangeException') if value is outside the range of   
     [rangeLo, rangeHi].
+- **[IEnumerableExtensions](Sagara.Core.IEnumerableExtensions.md 'Sagara.Core.IEnumerableExtensions')** `Class`
+  - **[Index&lt;TSource&gt;(this IEnumerable&lt;TSource&gt;)](Sagara.Core.IEnumerableExtensions.md#Sagara.Core.IEnumerableExtensions.Index_TSource_(thisSystem.Collections.Generic.IEnumerable_TSource_) 'Sagara.Core.IEnumerableExtensions.Index<TSource>(this System.Collections.Generic.IEnumerable<TSource>)')** `Method` Returns an enumerable that incorporates the element's index into a tuple.
 - **[SequentialGuid](Sagara.Core.SequentialGuid.md 'Sagara.Core.SequentialGuid')** `Class` Generates Guids sequentially.
   - **[SequentialGuid()](Sagara.Core.SequentialGuid.md#Sagara.Core.SequentialGuid.SequentialGuid() 'Sagara.Core.SequentialGuid.SequentialGuid()')** `Constructor` Default .ctor. Initializes [CurrentGuid](Sagara.Core.SequentialGuid.md#Sagara.Core.SequentialGuid.CurrentGuid 'Sagara.Core.SequentialGuid.CurrentGuid') with a new value.
   - **[SequentialGuid(Guid)](Sagara.Core.SequentialGuid.md#Sagara.Core.SequentialGuid.SequentialGuid(System.Guid) 'Sagara.Core.SequentialGuid.SequentialGuid(System.Guid)')** `Constructor` Constructor that initializes [CurrentGuid](Sagara.Core.SequentialGuid.md#Sagara.Core.SequentialGuid.CurrentGuid 'Sagara.Core.SequentialGuid.CurrentGuid') with the provided Guid.