CompTIA A+ Core 2 (220-1202), Domain 1, Objective 1.1 focuses on operating system compatibility concerns: the practical problems that surface when files, applications, and users move between different operating systems, different versions of the same operating system, and different processor architectures. A technician who understands these concerns can predict which programs will run, which files will open cleanly, and where a migration is likely to break before the user ever calls the help desk.
In this article you'll learn how to reason about compatibility between operating systems, how file and application portability works across platforms, why 32-bit and 64-bit application support matters, and how cross-platform file formats keep documents usable no matter which system opens them.