You can temporarily <strong>turn your own computer into a secure machine</strong>. You can also <strong>stay safe while using the computer of somebody else</strong>.
You don't have to worry about the computer having viruses because Tails runs independently from the other operating system and never uses the hard disk.But, Tails cannot always protect you if you install it from a computer with viruses or if you use it on a computer with malicious hardware, like keyloggers.