Tails

For those doing sensitive work or operating in dangerous online environments, Tails protects against many of the most common digital threats that at-risk individuals can face. Tails is not for everyone; while the usability of the system has come a long way in the last decade, it is still based on Linux and not as intuitive for most users as the Windows or Mac OS they are likely to be accustomed to. It is also the case that many of the fundamental choices in Tails mean that some things are more difficult; saving files and configuration choices are not automatic, the Tor network can be slower for connecting to the internet, and booting from a USB usually requires some configuration of a computer.

Tails is a computer operating system designed from the ground up for security; it is a version of Debian Linux, a free, open-source operating system. The name Tails is an acronym: “the” followed by a description of three key features: it is “amnesiac,” resetting itself to a known good start state every reboot and erasing all files; “incognito,” routing all internet traffic through the Tor network for anonymization; “live,” running off of a USB rather than a computer’s hard drive and therefore avoiding hard drive malware; and “system” denoting that it’s an operating system.

The trade-offs required for this level of security make some things more inconvenient. For example, Tails works best if most of your work is in the cloud because the process used for saving files is cumbersome.

Tails was originally designed to work on PCs compatible with Windows operating system, but can now be used on older Intel Macs as well, though not those powered by the newer Apple Silicon processors (M1, M2, etc). 

Cost

Free, though they welcome donations: https://tails.boum.org/donate/index.en.html

Maintenance considerations

Like all operating systems, Tails needs to be kept up to date with security considerations. 

Cybersecurity

Tails is as secure an operating environment as most of us will ever be able to use. The developers of Tails have made a series of choices that mean that, by default, using Tails will make you as safe as possible. However, no software can protect against all threats. Tails has written up some examples: https://tails.boum.org/doc/about/warnings/index.en.html. It's important to also follow other essential cybersecurity best practices, including those outlined in the Cybersecurity Handbooks for Civil Society Organizations, Political Parties or Parliaments.

• The Tails USB hosting the operating system and any saved files and configuration can be easy to lose. Make backup copies. 
• Using highly secure software like Tails can be seen as proof of having something to hide if observed by a repressive government.