480i is the video mode used for standard-definition analog or digital television in the Caribbean, Myanmar, Japan, South Korea, Taiwan, Philippines, Laos, Western Sahara, and most of the Americas (with the exception of Argentina, Paraguay, and Uruguay). The 480 identifies a vertical resolution of 480 lines, and the i identifies it as an interlaced resolution. The field rate, which is 60 Hz (or 59.94 Hz when used with NTSC color), is sometimes included when identifying the video mode, i.e. 480i60; another notation, endorsed by both the International Telecommunication Union in BT.601 and SMPTE in SMPTE 259M, includes the frame rate, as in 480i/30. The other common standard, used in the other parts of the world, is 576i.

SDTV resolution by nation; countries using 480i are in green.

In analogue contexts, this resolution is often called "525 lines". It is mandated by CCIR Systems M and J, which are usually paired with NTSC color - which led to the "NTSC" name being often inaccurately used to refer to this video mode. Other color encodings have also been used with System M, notably PAL-M in Brazil.