The Internet is a global network of billions of computers connected together to share data, while Wi-Fi is simply a wireless technology used to connect your devices to that local network. Think of the Internet as the water supply coming into your house through a main pipe, and Wi-Fi as the showerhead that sprays that water to your phone or laptop wirelessly. You can have a strong Wi-Fi signal but no Internet if the "main pipe" (your service provider) is down, just as you can access the Internet without Wi-Fi by using a cellular data plan or a physical Ethernet cable.