My setup

XAMPP runs on the same computer as my browser.

Remarks

• Important Safety Notice:
  The safe operation of the web server, that can be accessed from the internet, is not guaranteed by XAMPP, which is a development system!
• The same configuration on another webserver (e.g. apache, but not XAMPP) is ok!

ToDo-List

Follow it step by step!

1. Download XAMPP and install it at 'C:\xampp' (and NOT at 'C:\Program Files\xampp\' or similar!).
2. Check for 'httpd.conf' file at 'C:\xampp\apache\conf' and
   change

   # Virtual hosts
   #Include "conf/extra/httpd-vhosts.conf"
   

   to

   # Virtual hosts
   Include "conf/extra/httpd-vhosts.conf"
   

   only, if the "#" was in that row!

3. Now open 'httpd-vhosts.conf' from 'C:\xampp\apache\conf\extra' and add these lines
   

   <VirtualHost *:80>
       ServerAdmin postmaster@host.localhost
       DocumentRoot "C:/xampp/htdocs"
       ServerName localhost
       ServerAlias www.localhost
       ErrorLog "logs/host.localhost-error.log"
       CustomLog "logs/host.localhost-access.log" combined
   </VirtualHost>
   
   <VirtualHost *:80>
       ServerAdmin postmaster@dummy-host.localhost
       DocumentRoot "C:/xampp/htdocs/drupal"
       ServerName dummy-host.localhost
       ServerAlias www.dummy-host.localhost
       ErrorLog "logs/dummy-host.localhost-error.log"
       CustomLog "logs/dummy-host.localhost-access.log" combined
   </VirtualHost>
   
   <VirtualHost *:80>
       ServerAdmin postmaster@dummy-host2.localhost
       DocumentRoot "C:/xampp/htdocs/drupal"
       ServerName dummy-host2.localhost
       ServerAlias www.dummy-host2.localhost
       ErrorLog "logs/dummy-host2.localhost-error.log"
       CustomLog "logs/dummy-host2.localhost-access.log" combined
   </VirtualHost>
   

   If the file contains NameVirtualHost *:80 with a leading "#", remove the hash ("#").

4. Restart/reload your web server.
5. Now open file '%windir%\system32\drivers\etc\hosts' and add these 4 lines at end of file
   

   127.0.0.1    dummy-host.localhost
   127.0.0.1    dummy-host2.localhost
   127.0.0.1    www.dummy-host.localhost
   127.0.0.1    www.dummy-host2.localhost
   

6. Now download the latest recommended Drupal release,
   create a folder name "drupal" inside 'C:\xampp\htdocs\'
   and put all content of this drupal release (including the folder structure and its content) in this folder.
   Now you can find e.g. the file 'C:\xampp\htdocs\drupal\sites\default\default.settings.php', you need it.
7. Create 2 folder name
   a.) dummy-host.localhost
   and
   b.) dummy-host2.localhost
   inside of 'C:\xampp\htdocs\drupal\sites\'
8. Create 2 databases for 2 drupal sites (e.g. with name dummyhost and dummyhost2) using http://127.0.0.1/phpmyadmin/.
9. Open url
   a.) http://dummy-host.localhost/
   and
   b.) http://dummy-host2.localhost/
   and install them as standard drupal installation process (http://drupal.org/documentation/install).
10. Now Drupal "multisite installation" is done, you should look at
    a.) http://dummy-host.localhost/
    and
    b.) http://dummy-host2.localhost/
    for further installation.

SOURCE OF ARTICLES: https://www.drupal.org/docs/7/multisite-drupal/multi-site-on-windows-usi...