About IP addresses
What is IP address
IP (short for Internet Protocol), the principal communications protocol in the Internet, is method by which information is sent between any two Internet computers.
Every computer connected to the internet at given moment has a unique public address known as an IP address. An IP address is used to identify computers on the Internet.
How IP addresses work
IP address works like a return address would on a piece of mail. When your computer or device sends a request, like a search on Google, it tags the request with your IP address. That way Google knows where to send the response.
What an IP address looks like
The currently used IP addresses (IPv4) look like four blocks of digits ranging from 0 to 255 separated by a period like "172.18.0.255". In the new schema (IPv6) an IP address will be like "2a0c:b807:8000:c93a:ff51:90ac:0:153a".
Why does your IP address change
Usually the providers change the public IP address the user gets regularly, they assign a random address to each user when he connects to the internet and assign that same address to another user after he disconnects.