An IP address is the number that identifies your connection on the internet. Every website you visit sees it, and your internet provider assigns it to your router or phone.
IPv4 addresses have four numbers from 0 to 255, such as 203.0.113.24, which allows about 4.3 billion addresses. IPv6 was created because those ran out. It uses eight groups of hexadecimal digits, such as 2001:db8::5. Many networks now have both.