An Internet Protocol (IP) address is a unique numerical identifier assigned to each device connected to a network. It serves two fundamental purposes: identifying the host or network interface, and providing the location of the host in the network. Every time you load a webpage, send an email, or stream a video, IP addresses are working behind the scenes to route your data to the right destination.
When you type a domain name like example.com into your browser, the first thing that happens is a DNS (Domain Name System) lookup. Your computer asks a DNS resolver to translate that human-readable name into a machine-readable IP address — for example, 93.184.216.34.
Once your browser has the destination IP address, it breaks your request into small chunks called packets. Each packet is stamped with a source IP (yours) and a destination IP (the server's). Routers along the path read the destination IP and forward the packet to the next hop, guided by a global routing protocol called BGP (Border Gateway Protocol). This process repeats hop by hop until the packets reach the destination server.
Think of an IP address like a postal address: the IP identifies where to deliver data, just as your home address tells the post office where to deliver a letter. Packets are the individual envelopes, and routers are the sorting facilities that move them toward their destination.
Most people actually have two IP addresses at any given time: a public IP and a private IP. Your ISP assigns one public IP address to your home router. All the devices inside your home — phones, laptops, smart TVs — each get their own private IP address assigned by the router itself.
Private IP addresses fall within reserved ranges defined by RFC1918: 192.168.0.0/16, 10.0.0.0/8, and 172.16.0.0/12. These addresses are never routed on the public internet.
The technology that bridges your private network and the public internet is called NAT (Network Address Translation). When your laptop sends a request outward, your router rewrites the source IP from your private address to its own public IP. Responses come back to the router, which translates them back to your private address. This is why websites see your router's IP, not your device's IP directly.
Your public IP address exposes a limited but meaningful amount of information to any server you connect to:
What your IP address does not reveal: your full name, home street address, email, or any browsing history. That level of detail requires legal process served to your ISP, which keeps its own logs linking IP addresses to subscriber accounts.
Most residential internet connections use dynamic IP addressing. Your ISP runs a DHCP (Dynamic Host Configuration Protocol) server that leases IP addresses from a pool for a set period of time. When the lease expires — or when you restart your router — your IP may change. In practice, many ISPs reassign the same IP for months or years, but this is not guaranteed.
Static IP addresses are permanently assigned and never change. Businesses, web servers, and mail servers typically require static IPs because other systems need a reliable address to reach them. Static IPs are available from most ISPs for a monthly fee. If you want to run a home server, accept incoming connections, or use certain remote-desktop setups, a static IP — or a dynamic DNS service — is usually necessary.