A  cold computer is a secure computer that has never been connected to the  Internet, never will be, and cannot technically be connected to the  Internet. As we know, a secure computer has WiFi physically removed (or  physically disconnected or disabled at firmware level). A cold computer  has to be a secure computer because apparently ordinary computers (e.g.  with management engine) can connect to the WiFi also when the WiFi is  switched off.

Cold computers (especially if combined with Tails OS) provide an  ultra-secure environment to produce and work on very sensitive data,  such as important passwords or a Bitcoin wallet seed for example.

​

In  the next course on Bitcoin (Course 2), unless otherwise explicitly  stated, it will be assumed that all operations are made in a cold  computer.