The following key combinations are used to do things:

CTRL + M + M → Collapse / Expand current preset area (e.g. Method)

CTRL + M + H → Collapse / Hide (Expand) current selection

CTRL + M + O → Collapse all(Collapse declaration bodies)

CTRL + M + A → Collapse all

CTRL + M + X → Expand all

CTRL + M + L → Toggle all

There some options in the context menu under Outlining.

CTRL + M + L expands all

CTRL + M + O collapses all

In the MSDN article "Default Keyboard Shortcuts in Visual Studio," see the section "Text Editor" if you're looking for other shortcuts - these 2 are just a few of the many that are available.

CTRL+M expands region.

CTRL+L collapses region.

• Fold/Unfold the current code block – Ctrl+M, Ctrl+M
• Unfold all – Ctrl+M, Ctrl+L
• Stop outlining – Ctrl+M, Ctrl+P
• Fold all – Ctrl+M, Ctrl+O

In Visual Studio 2017, It seems that this behavior is turned off by default. It can be enabled under Tools > Options > Text Editors > C# > Advanced > Outlining > "Collapse #regions when collapsing to definitions"

CTRL + M + A collapses all

works for me, whereas

CTRL + M + O

does not

Press

CTRL + A

Then

CTRL + M + M

To compress all, including child nodes, in XML-files.

If you mean shortcut then

CTRL + M + M: This one will collapse the region your cursor is at whether its a method, namespace or whatever for collapsing code blocks, regions and methods. The first will collapse only the block/method or region your cursor is at while the second will collapse the entire region you are at.

In Visual Studio 2013:

CTRL + M + A collapses all

CTRL + M + L expands all

Are you refering to the toggle outlining?

You can do: Control + M then Control + L to toggle all outlining

Below are all what you want:

• Collapse / Expand current Method

CTRL + M + M

• Collapse / Expand current selection

CTRL + M + H

• Collapse all

CTRL + M + O

CTRL + M + A

• Expand all

CTRL + M + X

CTRL + M + L

To collapse all use:

Ctrl + M and Ctrl+A

All shortcuts for VS 2012/2013/2015 available at

None of these worked for me. What I found was, in the editor, search the Keyboard Shortcuts file for editor.foldRecursively. That will give you the latest binding. In my case it was CMD + K, CMD + [.

if you want to collapse and expand particular loop, if else then install following plugins for visual studio.

• VS2010
• VS2012
• VS2013
• VS2015

Collapse All - Ctrl + M + O

Expand All - Ctrl + M + L

In case of ugrading to Visual Studio 2010, 2012, 2013 or 2015, there's a Visual Studio extension to show current registered keyboard shortcuts, IntelliCommand.

Visual Studio can help you find the answer to your question in a couple of different ways.

Type Ctrl + Q to access Quick Launch, and then enter "collap". Quick Launch will display something like:^†

Menus (1)
    Edit -> Outlining -> Collapse to Definitions (Ctrl+M, Ctrl+O)
NuGet Packages (1)
    Search Online for NuGet Packages matching 'collap'

From there, enter "outlining" to find other menu entries related to outlining:

Menus (5)
    Edit -> Outlining -> Toggle Outlining Expansion (Ctrl+M, Ctrl+M)
    Edit -> Outlining -> Toggle All Outlining (Ctrl+M, Ctrl+L)
    Edit -> Outlining -> Stop Outlining (Ctrl+M, Ctrl+P)
    Edit -> Outlining -> Stop Hiding Current (Ctrl+M, Ctrl+U)
    Edit -> Outlining -> Collapse to Definitions (Ctrl+M, Ctrl+O)
Options (4)
    Text Editor -> Basic -> VB Specific (Change outline mode, Automatic inser...
    ...

However, note that Quick Launch will show you only those commands that are available as Visual Studio menu entries. To find other keyboard-related commands related to collapsing sections of code, in the Visual Studio menu bar click:

Tools -> Options -> Environment -> Keyboard

This will display the keyboard section in the Options dialog box. In the "Show commands containing" text box, enter "edit.collap". Visual Studio will display a list that is something like:

Edit.CollapseAllincurrentblock    
Edit.CollapseAllOutlining           Ctrl+M, Ctrl+A (Text Editor)
Edit.CollapseBlockcurrentblock
Edit.CollapseCurrentRegion          Ctrl+M, Ctrl+S (Text Editor)
Edit.CollapseTag                    Ctrl+M, Ctrl+T (Text Editor)
Edit.CollapsetoDefinitions          Ctrl+M, Ctrl+O (Text Editor)

You'll need to click each command to see its associated keyboard shortcut.

^† My examples taken from Visual Studio 2013.

For Visual Studio 2021 update.

I've been through all the answers but none worked for me for this update.

So posting a simple way to find out the shortcut as this shortcuts vary for different version. Go to Help → Keyboard Shortcut Preferences (Ctrl + K Ctrl + R) It will take you to this pdf which contains all the shortcuts. So search for your desired shortcut that is fold/collapse and use that in your function.

CTRL+Shift+[ → Fold (collapse) region

CTRL+Shift+] → Unfold (uncollapse) region

CTRL+K CTRL+[ → Fold (collapse) all subregions

CTRL+K CTRL+] → Unfold (uncollapse) all subregions

CTRL+K CTRL+0 → Fold (collapse) all regions

CTRL+K CTRL+J → Unfold (uncollapse) all regions

Once you get the shortcut key, You can go to the Keyboard Shortcuts (Ctrl + K Ctrl + S) and search for the shortcut key and replace it with your desired key.

In Visual Studio 2019:

Go to Tools > Options > Keyboard.

Search for Edit.ToggleAllOutlining

Use the shortcut listed there, or assign it the shortcut of choice.

In short, through "Tools … Settings":

If you want to collapse/expand an area within a class/method (instead of collapsing the entire class/method), you may create custom regions as follow:

 #region AnyNameforCollapsableRegion

 //Code to collapse

 #endregion 

Reference