Tails is an operating system optimized for anonymity that fits on a USB stick and can be used on any computer without leaving a trace. It’s used by the likes of Edward Snowden and Glenn Greenwald to keep their digital lives as secure as possible. The developers behind the OS remain anonymous, in part to help protect the code from government interference. The only storage space used is the RAM, which is automatically erased when the computer shuts down, so Tails can’t use the hard-disks.”]
Source: https://gizmodo.com/try-the-super-secure-usb-drive-os-that-edward-snowden-i-1563320487