What is an IP Address?
An IP address is a text code used to uniquely identify a computer connected to the Internet. Whenever a computer connects to another computer, such as a client to a server, or your web browser to a website, it does so by connecting to its IP address. Without the IP address of the computer, it's not possible to connect to it.
Today, there are two prevalent versions of the Internet Protocol (IP): IPv4 and IPv6.
An IPv4 address looks like this: 255.255.255.255. Four numbers from 0 to 255 separated by a dot (.). This can be parsed into 4 bytes, making it a 32-bit address capable of addressing four billion and something computers. Not ideal when we have more than four billion and something humans alive on planet Earth.
We don't talk about IPv5.
An IPv6 address looks like this: ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff. Eight numbers in hexadecimal from 0x0 to 0xFFFF separated by a colon (:). Each number is equivalent to from 0 to 65535 in decimal, or 2 bytes of data (16 bits), making the whole thing 16 bytes of data (128 bits). That's an extremely large number of addresses, so we probably won't have to worry about running out of them until we start colonizing other solar systems.