TAILS stands for “A living Incognito system with amnesia.” Every word in this phrase defines TAILS, as you will see soon.
TAILS for the OS is the same as TOR for browsers. For starters, it redirects everything through TOR. This anonymizes your traffic, actions, and most importantly, your IP address by default.
Did I mention that this is a LIVE operating system? This means that you can run it from a USB drive, no system installation is required! Yes, as soon as the USB is connected, it's gone!
Is someone trying to spy on you? It's useless. All data and traces that you even use TAILS are permanently deleted every time you turn off your system! This means that the files/websites you viewed, the devices you connected to, and all other data are gone, poof!
Please note that TAILS suffers from amnesia (from Amnesia), he forgets everything. However, it offers additional “permanent storage” options. You can choose to save some files, bookmarks, email services, etc. so that they are not erased when you restart.
Obviously, it has most of the best privacy tools you will ever need. These include an anonymous email client, an anonymous messenger, ad blockers, a browser (TOR) and more.
TAILS is 100% free and open source. It greatly increases trust, doesn't it? If that wasn't enough, Edward Snowden, the guy who revealed information about the NSA to the world, also recommends TAILS.