Abstract: An external operating system (OS) that is separate from the internal OS of a computer is provided. The external OS may be stored on a USB device, a CD ROM, or other devices. The device that stores the external OS may be removable or non-removable, may have an internal flash memory of varying sizes, and may include browser software. The external OS, flash memory size and browser software may be customizable according to user requirements. The computer may boot up from the device into the external OS, rather than into the internal OS of the computer. Once the computer is booted up, the user has the ability to browse online, with all transactions occurring in the external OS, partitioned from the user's internal computer hard drive, thereby preventing infecting the computer by malware or other malicious software.