IP Addresses are 4 numbers between 0-255, in a string separated by periods. Like 10.11.12.13

Every computer attached to the internet has its own unique IP Address. Your home likely has a modem with a unique IP Address. Ask Google “What is my IP Address”.  Like a phone number, you can communicate with other computers on the internet by entering their IP Address. A Domain Name and the Domain Name System is the equivalent of the phone book.