ReactOS is a free, open-source Windows NT-like operating system for both 32-bit and 64-bit personal computers, originally developed in 1996. It maintains system-level compatibility with Windows (including computer programs and device drivers developed for Windows Server 2003 and later versions of Windows), and is committed to becoming a perfect replacement for the Windows NT series.

The installation of Windows, Linux, or Mac operating system has been automated and foolproof for a long time, with no technical difficulty. But if you want to install and use multiple systems at the same time, whether it's a combination of multiple different versions of Windows or Windows + Linux + Mac (each has a different boot method), the hardest part is figuring out their installation order and adjusting the boot menu. This can be cumbersome and experience required even for advanced computer users.

Puppy Linux is one of the earliest lightweight Linux distributions, originally developed by Barry Kauler from Australia in 2003 (which is still active today). It is a very reliable operating system for both old computers and new Linux users! It is small in size, simple in structure, fast in speed, and comes with a wealth of drivers and applications. Even better, it can be installed and run directly on storage devices like external hard disks and USB flash drives (that is, it can be booted from any computer that supports BIOS and UEFI).

Ubuntu has become bloated and extremely slow (even has started to follow the trend of quickly refreshing the version number, and indulges in this disgusting behavior) for a long time, and its requirements for hardware configuration has far exceed those of Windows now. In other words, running an Ubuntu OS today means making your computer fan spinning at a full jump all the time. The noise of fan alone is painful enough. As a result, more and more people are abandoning Ubuntu, meanwhile increasing lightweight alternatives has emerged and are emerging, and many of them are even able to run smoothly on a USB device, not to mention HDD or SSD. Thereinto, Manjaro is one of the best.

The ever most widely used and important operating system was Windows 98. Its predecessor is Windows 95, which is a direct successor to Microsoft's prior standalone operating systems MS-DOS and Windows 3.1. As a major milestone of Microsoft's operating system, many of the classic features and designs that Windows 95 first introduced, such as the Start Menu, My Computer, as well as the classic card game - FreeCell, are still in use today.