There are currently 3 main television standards used throughout the world:

NTSC

National Television Standards Committee. The oldest existing standard, developed in the USA. First used in 1954. Consists of 525 horizontal lines of display and 60 vertical lines. Sometimes irreverently referred to as “Never Twice the Same Color.” Only one type exists, known as NTSC M.

SECAM

Système Électronique pour Couleur avec Mémoire. Developed in France. First used in 1967. A 625-line vertical, 50-line horizontal display. Sometimes referred to by wags as “Something Essentially Contrary to the American Method” or SEcond Colour Always Magenta!” Different types use different video bandwidth and audio carrier specs. Types B and D usually used for VHF; types G, H, and K for UHF; types I, N, M, K1 and L for both VHF/UHF. Different types are generally not compatible.

PAL

Phase Alternating Line. Developed by German engineer Walter Bruch and the German electronic corporation Telefunken. Walter Bruch
patented his invention 1963 and the first commercial application of the PAL system was in August 1967. Also a 625/50-line display and variant of NTSC. Proponents call it “Perfection At Last.” Due to the cost of the enormous circuit complexity, critics often refer to it as “Pay A Lot”. Different types use different video bandwidth and audio carrier specs. Common types are B, G and H; less common types include D, I, K, N and M. The different types are generally not compatible.