The cable and Internet company Comcast has begun a project to blanket Chicago with public WiFi using its existing service equipment. The project uses the equipment already in the homes of Comcast subscribers, the Chicago Tribune reported. A company official said subscribers' privacy and speed will not be at risk because the public WiFi signal will be separate from theirs. "They'll look like two separate networks and they'll act like two separate networks," Tom Nagel, who heads the Xfinity WiFi initiative for Comcast, told the Tribune. "Any use on the public side doesn't impact the private side." WiFi started about 15 years ago and became a perk for coffee shop patrons and a service at public libraries. Craig Moffett of MoffettNathanson, a telecommunications and cable research firm, said when wireless companies began charging for data downloads four years ago, WiFi became a lot more popular. "Suddenly, there was a huge economic incentive to rely on WiFi whenever it was available, and you started to see the consumption of WiFi go through the roof." XFinity customers will be able to log on to WiFi signals using their own credentials, the company said. Non-customers will get two free hours a month and will be able to pay by the hour if they want.