Norton Internet Security, developed by Symantec Corporation, provides malware prevention and removal during a subscription period and uses signatures and heuristics to identify viruses. Other features include a software firewall, e-mail spam filtering and phishing protection. Additional functionalities, such as parental controls, are available as extensions developed by Symantec.
Symantec distributes the product as a download, a box copy, or OEM software. Norton Internet Security and its sister product, Norton AntiVirus, combined, held a 61% antivirus market share as of 2007. Major competitors in terms of market share include antivirus products from vendors CA, Trend Micro, and Kaspersky Lab.