Why is Linux said to be a virus-free operating system?

Ya Linux is virus free OS, How??
Answer: Linux OS Extracted files and folders are kept hidden which cannot be accessed by viruses.
Now what are Viruses??
Viruses are the files which carry the path-name of the WINDOWS FOLDER present in Windows OS where all the functional .(DOT)dll files are stored. Once these .dll files get corrupted then the PC starts behaving like a mad bull.
So, these .dll kind (not the same format files) of files are also their in Linux OS but they are kept hidden, as a result the virus path cannot find them. Thus, no damage but still the files stored by the user on a Linux machine get corrupted.