Choose an option logout through the session indicator on the far right side of the top paner.

Open Source refers to a program or software in which the source code is available in the web to the general public free of cost.

File extension is used to know that in which the file is associated with.

Save - This will save the document without asking for a new name or location. It will overwrite the original.
Save As- This will prompt you to save the document using a dialog box. This allows to change the file name or location.

Use of Cortana
(i) Gives reminders based on time, places or people.
(ii) Track packages, teams, interests and flights.
(iii) Send emails and texts.
(iv) Find facts, files, places and information.
(v) Open any application on your system.

The drives are segregated because
(i) Save space and increase performance.
(ii) To include other Operating systems, isolate programs and keep files tidy.
(iii) It might help to isolate operating systems or programs from other user.

In Ubuntu OS:
(i) Create a file: By right-clicking in the desktop' and also files be created by using the file menu.
(ii) Delete a file: By using right-click choosing a move to trash or by using the menu.
(iii) Rename a file: By using right-click and choosing rename option.
(iv) Save a file: Press ctrl + x or F2 to exit. You will. then be asked if you want to save. (or) Press ctrl+ 0 or F3 and ctrl + x or F2 for save and exit.
In Windows OS:
(i) Create file: Open an application and create it by using the file menu.
(ii) Delete a file: By right click on a file and choosing the delete option to delete a file.
(iii) Rename a file: By right-clicking on a file and choosing rename option to rename a file.
(iv) Save file: Press ctrl+S or file - save to save the file.