Every computer/device connected to the Internet in one way or another has a specially assigned address, an Internet Protocol, also known as an IP address.
An IP address was originally a 32-bit number, but due to the rapid growth of the Internet an new version of IP was developed back in 1995 (128-bit). The old version was called IPv4, while the never version is called IPv6. The highest authority on IP addresses is the Internet Assigned Numbers Authority (IANA). They delegate IP addresses to regional Internet registries (RIRs) who again delegate it to Internet Service Providers who again give out IP addresses to users (you and me).
This means that IP addresses look different, depending on where you are in the world. Every RIR receive a certain window of IP addresses which they again give on to the ISPs, who agan give it on to their users. An IP address consists of four series of numbers and can for example look like this: 127.0.0.1. Another example of an IP address which is: 126.96.36.199.
Since the IP addresses are delegated from IANA to RIR to ISP to you it is easy to find out where you are located in the world and who your ISP is. They will not find out your exact whereabout, but with ease it is possible to find out what city you are staying in.
Many online sites take advantage of this knowledge and use a so called IP geo block on their services. This means that they lock people with IP addresses in other nations out, and only let people with an IP address in that given nation see the content.
- You can find answers to more IP Address related questions here.
Dynamic and static IP addresses
I get my IP address from my Internet Service Provider (ISP). They have received a pool of addresses which they can give out to their customers, and normally they do this using a DHCP server. The DHCP server notices when you try to connect to the Internet and automatically gives you a free IP address from the IP address pool given to your provider. This means that you do not have a constant IP address, but it changes regularly, normally at least once every 24th hour. That is why it is called a dynamic IP address, because it changes. Because of the address changing regularly that is not an good solution if you want to host websites and servers.
While a dynamic IP address changes regularly, a static IP address is a permanent IP address which do not change. If you have a static IP address you can easily use it for webhosting and hosting files and other things you want available online. If you want a static IP address from you Internet Service Provider you will often have to pay more, but if you need it, it is worth it.