With high-speed Internet common in most homes, hopping online is largely an instant and silent affair. But before many of today's kids were born, unconnected people had to take multiple steps get computers onto the Internet. It required dialing into your ISP (Internet Service Provider) using a phone number via an external (or later internal) dial-up modem. Older models even required placing a rotary phone headset onto a cradle on the modem. Connecting via a modem was noisy because it literally placed a phone call and sent analog signals over the phone lines. This would tie up the phone line, and the slow data-transfer method meant downloading and uploading took a while. Most kids today likely don't recognize the modem noise and don't know the torture of watching a picture draw itself onto the computer screen from the top down at a snail's pace.
Most mobile devices and WiFi-enabled modern computers detect any local WiFi networks automatically. You just have to choose the network you want to connect to (such as your home WiFi network), type your password and boom, you're off and running, able to simply open a browser and surf the Internet, or go to a built-in app store and download software and entertainment media. If your password is saved on your device, you may only have to do this once. And when smartphones don't have access to WiFi (or the WiFi is turned off), they simply connect by default to the carrier's cellular network, through which they can also send and receive Internet data.