diff --git a/README.org b/README.org
index 003133d..437497e 100644
--- a/README.org
+++ b/README.org
@@ -34,7 +34,7 @@ opportunity to learn about computers, files, directories and programs.
  * [[./tutorial/files_directories.org][Learning about files and directories]]
  * [[./tutorial/rsync.org][Using rsync to copy files]]
  * [[./tutorial/search_files.org][Searching for files in the system]]
- * [[./tutorial/diff.org][Comparing two files or directories: 'diff']] 
+ * [[./tutorial/diff.org][Comparing two files or directories: 'diff']]
  * [[./tutorial/diff_patch.org][Comparing two files and create a unified version: diff and patch]]
  * [[./tutorial/dd_command_flash_usb.org][Using dd command to flash usb]]
  * [[./tutorial/compress_pdf.org][Compress a pdf file]]
@@ -42,10 +42,14 @@ opportunity to learn about computers, files, directories and programs.
  * [[./tutorial/pacman.org][Use package manager in Parabola GNU-linux: verify packages in cache]]
  * [[./tutorial/removing_packages.org][Removing packages in Parabola GNU-Linux]]
 
+** Secure shell ssh and file transfer
+
+ * [[./tutorial/copy_server.org][Transfering files between machines]]
+
 ** Work with images
 
  * [[./tutorial/image_size_reduction.org][Reduce image quality and size from terminal]]
- 
+
 ** Disk space utilization and manipulation
 
  * [[./tutorial/ncdu.org][Exploring disk space with 'ncdu']]
diff --git a/tutorial/copy_server.org b/tutorial/copy_server.org
new file mode 100644
index 0000000..c260f84
--- /dev/null
+++ b/tutorial/copy_server.org
@@ -0,0 +1,64 @@
+#+date: 2023-08-20
+#+options: toc:nil num:nil author:nil
+
+* Transfering files
+
+Let's say you want to transfer files, images or directories between a local
+machine and a server. What could be a good option?
+
+There are multiple free software options to transfer file between machines:
+
+ * [[https://wiki.archlinux.org/title/Rsync][rsync]]
+ * [[https://man.archlinux.org/man/sftp.1.en][sftp]] (secury file transfer protocol)
+ * [[https://wiki.archlinux.org/title/SCP_and_SFTP][scp]] (secure copy protocol)
+
+** rsync
+
+For example: transfering all the ~.jpg~ files in the directory to a server:
+
+#+begin_example sh
+  rsync -a -P -e "ssh -p 2222" ./*.jpg root@186.76.90.145:/root/img/
+#+end_example
+** scp
+
+** Using ~sftp~ to copy files
+
+~sftp~ can be used to transfer files from a local machine to a server. The
+protocol allows to access the server, visualize, manipulate and transfer
+files from and to a server. You need to configure ~ssh~ access to the
+server from your local machine.
+
+A server can be accessed from a local machine following this logic:
+
+#+begin_example sh
+  sftp -P 2222 root@186.76.90.145
+#+end_example
+
+The command ~sftp~ followed by the port and user@ip_address.
+
+After accessing the server, files can be download from the server:
+
+#+begin_example sh
+ sftp> get file_in_server
+#+end_example
+
+You can also transfer files to the server:
+
+#+begin_example sh
+ sftp> put file_in_local_machine
+#+end_example
+
+
+To exit from ~sftp~ use:
+
+#+begin_example sh
+ sftp> put file_in_local_machine
+#+end_example
+
+There are additional options to use ~sftp~. Check the manual to know more about:
+
+#+begin_example sh
+  info sftp
+#+end_example
+
+** References
diff --git a/tutorial/image_size_reduction.org b/tutorial/image_size_reduction.org
index c54f307..0be960a 100644
--- a/tutorial/image_size_reduction.org
+++ b/tutorial/image_size_reduction.org
@@ -3,14 +3,32 @@
 
 * Use imagemagick to manipulate images
 
+[[https://imagemagick.org/][ImageMagick]] is a suite of tools used for digital image edition and manipulation.
+The tools can be used in the command line (~cli~).
+
+There are multiple functionalities avaliable in ImageMagick. Commands like ~convert~,
+~mogrify~ and ~identify~ are just some of the useful tools available.
+
+** Using the ~convert~ command
 
 Converting multiple ~jpg~ files into lower size images:
 
+First, [][cd] into the directory containing all the images
+#+begin_example sh
+  cd directory
+#+end_example
+
+Then use ~convert~ to resize all the 'jpg' files within the directory:
+
 #+begin_example sh
   convert '*.jpg' -set filename:fn '%[basename]-small' -resize 960x640 '%[filename:fn].jpg'
 #+end_example
 
-convert <INPUT_FILE> -quality 10% <OUTPUT_FILE>
+Here the '%[basename]-small' will copy original files, resize and rename including
+the suffix "small" to the original name.
+
+Reduce quality using convert (the command is similar to the previous one, but
+it uses ~-quality~ instead of ~-resize~)
 
 #+begin_example sh
   convert '*.jpg' -set filename:fn '%[basename]-small' -quality 50%  '%[filename:fn].jpg'
@@ -18,17 +36,29 @@ convert <INPUT_FILE> -quality 10% <OUTPUT_FILE>
 
 ** Using mogrify
 
+~mogrofy~ can be used for similar purposes.
+
+Let's check som images in a directory to verify how much those images can be
+modified.
+
+Change directory use the commands in the same place were the images are included,
+e.g:
+
+#+begin_example sh
+  cd directory
+#+end_example
+
 Counting number of ~.jpg~ images in a directory:
 
 #+begin_example sh
   ls -1U DIR_NAME | wc -l
 #+end_example
 
-Output:
+Verify the output:
 
-75 
+75
 
-Verifying the images weight:
+Verifying the images weight of all the images:
 
 #+begin_example sh
   du -h
@@ -48,6 +78,8 @@ Output:
 
 42M
 
+Reduce the quality of all the images within the directory:
+
 #+begin_example sh
   mogrify -quality 80% *.jpg
 #+end_example
@@ -62,9 +94,54 @@ Output:
 
 12M
 
+** Remove some metada from images
+
+[[https://imagemagick.org/script/command-line-options.php#strip][`mogrify -strip`]]can be used to remove some metada from the images.
+
+First you can check the image metada using the command ~identify~ from Imagemagick.
+
+#+begin_example sh
+  identify -verbose image.jpg
+#+end_example
+
+This command will print an output like this:
+
+ # Filename: image.jpg
+ #  Permissions: rw-r--r--
+ #  Format: JPEG (Joint Photographic Experts Group JFIF format)
+ #  Mime type: image/jpeg
+ #  Class: DirectClass
+ #  Geometry: 960x640+0+0
+ #  Resolution: 72x72
+ #  Print size: 13.3333x8.88889
+ #  Units: PixelsPerInch
+ #  Colorspace: sRGB
+ #  Type: TrueColor
+ #  Base type: Undefined
+ #  Endianness: Undefined
+ #  Depth: 8-bit
+ #  Channels: 3.0
+ #  Channel depth:
+ #    Red: 8-bit
+ #    Green: 8-bit
+ #    Blue: 8-bit
+ #  Channel statistics:
+ #  Pixels: 614400
+ # ...
+ # ...
+ # Version: ImageMagick 7.1.1-12 Q16-HDRI x86_64 21239 https://imagemagick.org
+
+You can use ~mogrify~ to remove metada from one or multiple images using
+something like:
+
+#+begin_example sh
+  mogrify -strip ./image.jpg # one image
+  mogrify -strip ./*.jpg # modifiyng all 'jpg' files in directory
+#+end_example
+
+
 ** References
 
 - [[https://askubuntu.com/questions/1354205/imagemagick-convert-on-a-multiple-files][Imagemagick to convert multiple files]]
 - [[https://imagemagick.org/][Imagemagick web site]]
 - [[https://www.digitalocean.com/community/tutorials/reduce-file-size-of-images-linux][Digital ocean tutorial]]
-