Macintosh operating system (Mac OS) Apple Inc ka design kiya gya operating system (OS) hai jise Apple Macintosh series ke computer pe install karne ke liye design kiya gya hai. Mac OS ko 1984 me introduce kiya gya joki ek graphical user interface (GUI) based OS hai jise tab se abtak kayi different series me release kiya ja chuka hai. Initially Mac OS ko System Software ke naam se jana jata tha.
Mac OS functionality aur services me Windows or Linux OS ki tarah hi hai, par isme Lisa OS ke kuch feature incorporate kiya gaye hai. Mac OS ko Apple manufactured PCs ko operate karne ke liye design kiya gya hai aur by default x86 architecture ko support nahi karta hai.
Mac OS ka first version “Classic” macOS series ka part tha joki mid-1980s me release kiya gya tha. Isme command line nahi diya gya tha aur ye ek baar me sirf ek hi application ko run kar skata tha. Macintosh operating system ka pahla version jise “macOS” naam diya gya tha version 7.6 tha. Recent version ko macOS X, or macOS kaha jata hai.