Windows NT, which was aimed at professional users such as networks and businesses, used a similar but separate version number between 3.1 and 4.0.

In addition to improved capabilities given to native applications, Windows also allowed users to better multitask older MS-DOS-based software compared to Windows/386, thanks to the introduction of virtual memory.

A subset of features from Cairo were eventually added into Windows NT 4.0 released on August 24, 1996, albeit without the object file system.

After Windows 3.11, Microsoft began to develop a new consumer oriented version of the operating system code-named Chicago.

Chicago was designed to have support for 32-bit preemptive multitasking, that of which was available in OS/2 and Windows NT, although a 16-bit kernel would remain for the sake of backward compatibility.

The Win32 API first introduced with Windows NT was adopted as the standard 32-bit programming interface, with Win16 compatibility being preserved through a technique known as "thunking".

Microsoft did not change all of the Windows code to 32-bit; parts of it remained 16-bit (albeit not directly using real mode) for reasons of compatibility, performance and development time.

Microsoft marketing adopted Windows 95 as the product name for Chicago when it was released on August 24, 1995.

Windows 98 Second Edition also has certain improvements over the original release, and hardware support through device drivers was increased.

Windows Me initially gained a positive reception upon its release, but later on it was heavily criticized by users for its instability and unreliability, due to frequent freezes and crashes.

[16] Microsoft DirectX, a set of standard gaming APIs, stopped being updated on Windows 95 at version 8.0a.

[21] The growing number of important updates caused by the end of life service for these operating systems have slowly made Windows 9x even less practical for everyday use.

Today, even open source projects such as Mozilla Firefox will not run on Windows 9x without major rework.

[26] Windows 9x/Me set aside two blocks of 64 KiB memory regions for GDI and heap resources.

As Windows became more complex and incorporated more features, .INI files became too unwieldy for the limitations of the then-current FAT filesystem.

Windows 9x supports .INI files solely for compatibility with those applications and related tools (such as setup programs).

Both the VMM and virtual device drivers run in a single, 32-bit, flat model address space at privilege level 0 (also called ring 0).

The FAT file systems provide no access control lists and file-system level encryption like NTFS.

This enables viruses and other clandestinely installed software to integrate themselves with the operating system in a way that is difficult for ordinary users to detect or undo.

Windows 95's default login dialog box also allows new user profiles to be created without having to log in first.

Users and software are also free to change configuration files in such a way that the operating system is unable to boot or properly function.

This phenomenon is not exclusive to Windows 9x; many other operating systems are also susceptible to these vulnerabilities, either by viruses, malware or by the user’s consent.

Additionally, the message server performs several background functions, including loading the Windows shell (such as Explorer.exe or Progman.exe).

Windows 9x has no native support for hyper-threading, Data Execution Prevention, symmetric multiprocessing, APIC, or multi-core processors.

[32][33] Hardware driver support for Windows 98/Me began to decline in 2005, most notably with motherboard chipsets and video cards.

According to Microsoft developer Raymond Chen, MS-DOS served two purposes in Windows 95: as the boot loader, and as the 16-bit legacy device driver layer.

These VxDs allow Windows 9x to interact with hardware resources directly, as providing low-level functionalities such as 32-bit disk access and memory management.

The second role of MS-DOS (as the 16-bit legacy device driver layer) was as a backward compatibility tool for running DOS programs in Windows.

A 16-bit driver called IFSMGR.SYS would previously have been loaded by CONFIG.SYS, the job of which was to hook MS-DOS first before the other drivers and programs got a chance, then jump from 16-bit code back into 32-bit code, when the DOS program had finished, to let the 32-bit file system manager continue its work.

Windows 93 (stylized as "WINDOWS93" in the title) is a web-based parody site created by two French musicians and programmers who go by the names of jankenpopp and Zombectro.