Open startup folder in Windows 10

To open system level(common) startup location using Run dialog (WinKey+r), type:

shell:common startup

To open current user's startup location:

shell:startup

or from the command line (cmd.exe) do:

explorer.exe shell:common startup

Reference(s):
http://8thstring.blogspot.com/2013/08/open-all-users-start-up-folder-in.html
http://www.winhelponline.com/blog/shell-commands-to-access-the-special-folders/
http://www.osattack.com/windows-7/huge-list-of-windows-7-shell-commands/
http://support.microsoft.com/kb/2806079