FOR /D

Conditionally perform a command on several Directories/Folders.

Syntax
      FOR /D [/r] %%parameter IN (folder_set) DO command

Key
   folder_set  : A set of one or more folders. Wildcards must be used.

   command     : The command to carry out, including any
                 command-line parameters.

   %%parameter : A replaceable parameter:
                 in a batch file use %%G (on the command line %G)

   /r          : Recurse into subfolders (see notes below)

In all cases for /d will start searching from the current directory.

Unlike other variants of the FOR command you must include a wildcard (either * or ?) in the 'folder_set' to get consistent results returned. In many cases you can work around this by adding a single character wildcard e.g. if you are looping through multiple folders to find the exact folder January you could instead specify Janu?ry

The option /d /r is undocumented, but can be a useful combination, the wildcard will only match against Folder/Directory names (not filenames).

An alternative command to list folders and sub folders matching a wildcard is DIR:
C:\> dir /b /s /a:d "C:\Work\reports*"

Wrapping that in a FOR /f command will loop through each folder:
C:\> for /f "tokens=*" %G in ('dir /b /s /a:d "C:\Work\reports*"') do echo Found %G

or the same thing within a batch file, with the %'s doubled:
for /f "tokens=*" %%G in ('dir /b /s /a:d "C:\Work\reports*"') do echo Found %%G

Example

List every subfolder, below the folder C:\Work\ that has a name starting with "User":

C:\> CD \Work
C:\> FOR /D /r %G in ("User*") DO Echo We found %G

FOR is an internal command.

"I knew of one little DO loop that ran for 48 hours, cost $14,000 and did nothing" ~ Balfour and Marwick

Related:

FOR - Loop commands
FOR - Loop through a set of files in one folder
FOR /R - Loop through files (recurse subfolders)
FOR /L - Loop through a range of numbers
FOR /F - Loop through items in a text file
FOR /F - Loop through the output of a command
FORFILES - Batch process multiple files
GOTO - Direct a batch program to jump to a labelled line
IF - Conditionally perform a command
Powershell: ForEach-Object - Loop for each object in the pipeline
Equivalent bash command (Linux): for - Expand words, and execute commands