In C#, any opening parenthesis, bracket, brace or quote (altogether called "delimiters") can be highlighted with color or outline whenever you place the caret at the corresponding closing delimiter, and vice versa.
Note
See
Highlighting matching C# braces with color:
Highlighting matching C# braces with outline:
In VB.NET, matching Sub or Function keywords are highlighted when the caret is placed anywhere within or after End Sub or End Function.
Should a matching delimiter/keyword be left out of scrolling view in the editor, it displays in a tooltip.
Displaying matching C# braces in a tooltip:
Displaying matching VB.NET keywords in a tooltip:
