Starting with Visual Studio 2017, statement collapsing is built-in.
There are several extensions that perform this task for pre-2017 versions of VS, starting with VS 2010 version:
- C# outline
- C# outline
2012 (@MSDN) - C# outline
2013 (@MSDN) - C# outline
2015 (@MSDN) - Visual Basic and C# Outliner
The last extension supports only VS 2015 and VS 2017, but it’s the most powerful one.
It supports syntax coloring inside collapsed blocks, it is more fault-tolerant and optimized.
If the extension doesn’t seem to install after you used a browser to download it, try using the built-in Visual Studio extension manager.