First, open Notepad. Then copy and paste into it the text on the line below. (It should all be on one line.)

X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*

Then select File, Save, select All Files for the file type, then save the file as eicar.com. The result should look exactly like the screenshot below:

Your anti-virus software may prevent you from saving the file as eicar.com, which is a sign that it is working effectively. If it doesn’t raise an alert, try scanning the folder where you saved eicar.com. To see what happens if you try to run a file containing a virus, double-click eicar.com to open it.

Explanation
The file eicar.com you have created is completely safe. It is not a virus. It is a standard test file developed by the European Institute for Computer Anti-virus Research (EICAR). All anti-virus products are programmed to detect this file as if it was a real virus. Therefore you can safely use it to test whether your anti-virus software works, without fear of infecting your computer.

If your anti-virus product should fail to prevent you from running the file, it will simply display the text “EICAR-STANDARD-ANTIVIRUS-TEST-FILE” in a DOS box. No harm will have been done, but you should probably consider using a better anti-virus product, because if it had been a real virus, your computer would by now be infected!