Searching for network help often surfaces both public IP and private IP and confuses beginners. Here is a clear summary of why both exist and how they differ.
Imagine sending a package. - **Public IP:** A unique street address like 123 Teheran-ro, Gangnam-gu, Seoul that works worldwide. - **Private IP:** Desk labels inside the building such as Kim's desk or Lee's desk. A friend abroad can mail your building (public IP), but writing only Kim's desk (private IP) on the envelope will never reach you — the same principle applies on the internet.
Key differences: - **Assigned by:** Public IP — ISP, globally unique. Private IP — your router, may overlap across homes. - **External direct access:** Public IP — reachable worldwide with permission. Private IP — only devices on the same Wi-Fi can talk directly; the public internet cannot route to it.
IANA reserved ranges for internal use only: - **Class A private:** 10.0.0.0 ~ 10.255.255.255 - **Class B private:** 172.16.0.0 ~ 172.31.255.255 - **Class C private:** 192.168.0.0 ~ 192.168.255.255 (most common on home routers) Public IPs never use these private ranges.