Internet, Networking, & Security Home Networking Internet Connection Sharing (ICS) Definition By Melanie Pinola Writer Former Lifewire writer Melanie Pinola has 5+ years' experience writing about consumer-oriented technology and is an expert telecommuter. our editorial process Melanie Pinola Updated June 24, 2019 10,000 Hours/Getty Images Home Networking The Wireless Connection Routers & Firewalls Network Hubs ISP Broadband Ethernet Installing & Upgrading Wi-Fi & Wireless Tweet Share Email Definition Internet Connection Sharing, or ICS, is a built-in feature of Windows computers (Windows 98, 2000, Me, and Vista) that allows multiple computers to connect to the Internet using one single Internet connection on one computer. It's a type of local area network (LAN) that uses a single computer as the gateway (or host) through which other devices connect to the Internet. Computers wired to the gateway computer or connecting to it wirelessly via an ad-hoc wireless network can use ICS. Some of the Features Allowing most any kind of device (including non-Windows and older Windows systems) to connect without having to install additional client software.Support for all of the connected clients to use many different protocols, including VPN and Internet gaming.Clients are automatically given an IP address and configured for DNS through the ICS computer. In Windows 98 or Windows Me, ICS needed to be enabled or installed on the host computer from the Control Panel Add/Remove Programs (on the Windows Setup tab, double-click on Internet Tools, then select Internet Connection Sharing). Windows XP, Vista, and Windows 7 have this built-in already (look in the Local Area Connection properties for a setting under the Sharing tab to "Allow other network users to connect through this computer's internet connection"). Note: ICS requires the host computer to have a wired connection to a modem (e.g., DSL or cable modem) or an aircard or other mobile data modem, and the client computers either wired to your host computer or connecting to it via the host computer's free wireless adapter. ICS for Different Versions of Windows and Mac How to Share Internet Access on Windows XPHow to Share an Internet Connection on VistaHow to Share an Internet Connection on Windows 7You can also Share Your Mac's Wired Internet Connection via Wi-Fi (doesn't use ICS, but is similar) Examples: To share one Internet connection among several computers you can either use a router or, on Windows, enable Internet Connection Sharing so that other computers connect to one computer that has an Internet connection.