GreenBorder was a security software company that specialized in using virtualization to create safe zones for online activities for Internet users. GreenBorder let computer operators combine hardware and software to create "virtual" machines where tasks such as reading e-mail or exploring websites could be done without exposing systems to viruses or other malicious programs. Web-based programs that try to access files or computer registries are stopped from leaving what are commonly referred to as online "sandboxes" created by GreenBorder. The virtual "sandboxes" vanish at the end of each session, taking attacker assaults such as spyware, viruses, and trojans with them.