Guides

IP and request guides

Short explanations for common IP, network, browser, and HTTP request terms.

IP address

A plain-English guide to IP addresses, public IPs, IPv4, IPv6, and what websites can infer from an address.

Understand the practical difference between IPv4 and IPv6 addresses, address length, notation, and network ranges.

Learn what CIDR notation means, how prefix lengths work, and how CIDR ranges apply to IPv4 and IPv6 networks.

Learn the difference between public IP addresses, private local addresses, NAT, and why websites usually see your router or VPN.

Understand Autonomous System Numbers, network owners, routing context, and why ASN data appears in IP lookup tools.

Learn what a user-agent string is, what browser and bot signals it can contain, and why it should not be treated as proof.

Understand HTTP request headers, common fields, proxy headers, sensitive headers, and what ShowIP exposes safely.