Adding Substring term. (#5580)

* Adding substring entry term

* Fixes a typo

* Fixes more typos

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update substring.md

Minor fixes

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Update content/c-sharp/concepts/strings/terms/substring/substring.md

* Prettier formatting

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Author: TheAireon

content/c-sharp/concepts/strings/terms/substring/substring.md

@@ -0,0 +1,95 @@
+---
+Title: '.Substring()'
+Description: 'Returns the substring of a string instance starting at a given index.'
+Subjects:
+  - 'Code Foundations'
+  - 'Computer Science'
+Tags:
+  - 'Methods'
+  - 'Strings'
+CatalogContent:
+  - 'learn-c-sharp'
+  - 'paths/computer-science'
+---
+
+The **`.Substring()`** method is a string method that returns a substring of a string starting at the specified index. It will return all characters from that index to the end unless a maximum length is specified. If the starting index equals the string length, it returns an empty string (`""`). If the index is greater than the string length, it throws an `ArgumentOutOfRangeException`.
+
+## Syntax
+
+```pseudo
+.Substring(int startIndex)
+```
+
+Or, alternatively:
+
+```pseudo
+.Substring(int startIndex, int length)
+```
+
+- `startIndex`: The index from where the substring starts.
+- `Length` (Optional): The number of characters to include in the substring..
+
+## Example
+
+In this example, `.Substring()` is used to return the substring of "Codecademy" starting at index `4` and includes all characters from that position to the end of the string:
+
+```cs
+using System;
+
+public class Program
+{
+    public static void Main()
+    {
+        string str = "Codecademy";
+        Console.WriteLine(str.Substring(4));
+    }
+}
+```
+
+The above example results in the following output:
+
+```shell
+cademy
+```
+
+## Example 2
+
+In this example, `.Substring()` is used with the optional `length` parameter to return a substring of 6 characters starting from index `2` of the string `"Codecademy"`.
+
+```cs
+using System;
+
+public class Program
+{
+    public static void Main()
+    {
+        string str = "Codecademy";
+        Console.WriteLine(str.Substring(2, 6));
+    }
+}
+```
+
+The above code generates the following output:
+
+````shell
+decade
+
+## Codebyte Example
+
+The below code demonstrates how to use the Substring method:
+
+```codebyte/csharp
+using System;
+
+public class Example
+{
+    public static void Main(string[] args)
+    {
+        string Name1 = "Brad";
+        string Name2 = "Angelina";
+
+        Console.WriteLine(Name1.Substring(1));
+        Console.WriteLine(Name2.Substring(1));
+    }
+}
+````