An ISP is a business that sells you a connection from your computer or phone to the rest of the internet. You pay them, and they give you the pipe — through a wall socket, a mobile signal, or both — so your device can send and receive. In everyday talk people also say internet company, or in Taiwan they simply name the firm on the bill. Though actually, younger users may barely say ISP at all; they say they have Wi-Fi or the internet, and the company stays in the background until the line dies. The letters name the firm that provides the pipe. They do not name the little box in your house, and they are not an IP address, which is a number given to a device on the network. One company can be your phone firm and your ISP at the same time; that does not make the two words the same thing.