Adobe Reader 9 is a freely downloadable, legacy application used to open, read, interact with, and print Adobe PDF (Portable Document Format) files. It serves as the viewing counterpart to the premium creation tool, .

Software is a constant battle between developers and hackers. Since Adobe Reader 9 is no longer supported, it receives no security patches. Hackers have had years to discover vulnerabilities in its code. Opening a malicious PDF with Reader 9 could compromise your entire system.