Windows 2000 (known as Windows NT 5.0 during development) is an NT-based version of Windows released by Microsoft. It succeeded Windows NT 4.0. Its Professional SKU was replaced by Windows XP, while its Server SKUs were replaced by Windows Server 2003. Windows 2000 was the last NT-based Windows product before the unification of the Windows NT and DOS-based line. It reached general availability on 2000-02-17. Windows 2000 targeted both the high-end consumer market, as well as server and business markets. Multiple SKUs were made for both client and server uses, albeit the user interface remains largely the same. Even though Windows 2000 was intended mainly for use in businesses unlike Windows Me, which was more targeted at home users, many home users ended up buying the Professional SKU of Windows 2000 during the time due to Windows Me’s negative reception.
During the course of its support, four Service Packs and an update rollup were released for Windows 2000. Microsoft had originally intended to release a fifth service pack for Windows 2000, but eventually canceled it, and in 2005 instead released the Update Rollup 1 for Windows 2000 Service Pack 4, a collection of all the security-related hotfixes and some other significant issues. The Update Rollup does not include all non-security related hotfixes and is not subjected to the same extensive regression testing as a full-service pack. Microsoft states that this update will meet customers' needs better than a whole new service pack, and will still help Windows 2000 customers secure their PCs, reduce support costs, and support existing computer hardware. Microsoft ceased support for Windows 2000 on 2010-07-13, over 10 years since its release.
Prior to the final announcement, Windows 2000 was called Windows NT 5.0 both in marketing materials and the operating system builds themselves. On 1998-10-27, Microsoft announced the renaming of the Windows NT 5.0 product line to Windows 2000, which according to Microsoft reflects the growing mainstream role of Windows NT. The name continues the year-based naming scheme for consumer-oriented versions of Windows, which started with Windows 95. This reflected the initial plan for Windows 2000 to succeed both the consumer-oriented Windows 98 and business-oriented Windows NT 4.0 operating systems. However, in the end, Windows Millenium Edition was released to succeed Windows 98, which led to confusion between the two. Due to the removal of the NT moniker, Windows 2000 branding often included the "Based on NT technology" tag line to clear out doubts.
An internal Microsoft presentation released during the U.S. v. Microsoft trial titled "Windows Launch Review" from 21 November 1997 briefly discusses naming options of the workstation edition. According to the document, Microsoft considered the following names:
- Windows NT Workstation 5.0
- Windows NT Client 5.0
- Windows NT Desktop 5.0
- Windows NT 5.0
- Windows 99/2000
There are 4 major editions of Windows 2000. One of the server editions, Windows Small Business Server 2000, is technically considered a separate version. Files from the IA-64 compile of Windows Server 2003 Build 2462 show a "Windows 2000 Personal" login banner, which indicates that such edition could also have been in planning. A version of Windows 2000 Advanced Server, known as Windows Powered, was made for network-attached storages - abbreviated to NAS. Windows Powered is only obtained using a utility created by Microsoft - known as Microsoft Server Appliance Kit - that converts Advanced Server to Powered.
- Windows 2000 Professional
- Windows 2000 Server
- Windows 2000 Advanced Server
- Windows 2000 Datacenter Server
Here are the information the edition that was borrowed from Wikipedia, the free encyclopedia.
It is the client version of Windows 2000. It offers greater security and stability than many of the previous Windows desktop operating systems. It supports up to two processors, and can address up to 4 GB of RAM. The system requirements are a Pentium processor (or equivalent) of 133 MHz or greater, at least 32 MB of RAM, 650 MB of hard drive space, and a CD-ROM drive (recommended: Pentium II, 128 MB of RAM, 2 GB of hard drive space, and CD-ROM drive).
It shares the same user interface with Windows 2000 Professional, but contains additional components for the computer to perform server roles and run infrastructure and application software. A significant new component introduced in the server versions is Active Directory, which is an enterprise-wide directory service based on LDAP. Additionally, Microsoft integrated Kerberos network authentication, replacing the often-criticised NTLM authentication system used in previous versions. This also provided a purely transitive-trust relationship between Windows 2000 domains in a forest (a collection of one or more Windows 2000 domains that share a common schema, configuration, and global catalog, being linked with two-way transitive trusts). Furthermore, Windows 2000 introduced a Domain Name Server which allows dynamic registration of IP addresses. Windows 2000 Server supports up to 4 processors, requires 128 MB of RAM and 1 GB hard disk space, however requirements may be higher depending on installed components.
Also known as Enterprise Server.
It is a variant of Windows 2000 Server operating system designed for medium-to-large businesses. It offers clustering infrastructure for high availability and scalability of applications and services, including main memory support of up to 8 gigabytes (GB) on Physical Address Extension (PAE) systems and the ability to do 8-way SMP. It supports TCP/IP load balancing and enhanced two-node server clusters based on the Microsoft Cluster Server (MSCS) in Windows NT Server 4.0 Enterprise Edition. Limited number of copies of an IA-64 version, called Windows 2000 Advanced Server, Limited Edition were made available via OEMs. System requirements are similar to those of Windows 2000 Server, however they may need to be higher to scale to larger infrastructure.
It is a variant of Windows 2000 Server designed for large businesses that move large quantities of confidential or sensitive data frequently via a central server. Like Advanced Server, it supports clustering, failover and load balancing. Its minimum system requirements are normal, but it was designed to be capable of handing advanced, fault-tolerant and scalable hardware—for instance computers with up to 32 CPUs and 64 GBs RAM, with rigorous system testing and qualification, hardware partitioning, coordinated maintenance and change control. Limited number of copies of an IA-64 version, called Windows 2000 Datacenter Server, Limited Edition were made available via OEMs. System requirements are similar to those of Windows 2000 Advanced Server, however they may need to be higher to scale to larger infrastructure.
There are 4 service packs of Windows 2000.
Windows 2000 SP4 is the latest version.
Microsoft had originally intended to release a fifth service pack for Windows 2000, but Microsoft cancelled this project early in its development, and instead released Update Rollup 1 for SP4, a collection of all the security-related hotfixes and some other significant issues.The Update Rollup does not include all non-security related hotfixes and is not subjected to the same extensive regression testing as a full service pack. Microsoft states that this update will meet customers' needs better than a whole new service pack, and will still help Windows 2000 customers secure their PCs, reduce support costs, and support existing computer hardware.
Service Pack 1
Service Pack 1 has been released on 2000-09-15.
Service Pack 2
Service Pack 2 has been released on 2001-05-16.
Service Pack 3
Service Pack 3 has been released on 2002-09-29.
Service Pack 4
Service Pack 4 has been released on 2003-06-26.
Update Rollup 1
Update Rollup 1 for Service Pack 4 is a collection of hotfixes, mainly for the security-related issues. It is said to contain all the security-related hotfixes and some non-security updates released between SP4 and UR1 for SP4. This rollup has been released instead of Service Pack 5. 
About Service Pack 5
Microsoft planned to release Service Pack 5, but it has been cancelled and Update Rollup for SP4 has been released instead. 
Leaking of source code
In early 2004, a portion of the Windows 2000 source code leaked online, together with the source code of Windows NT 4.0. The source of the leak was traced to Mainsoft, the developer of MainWin, a program allowing porting of Windows programs to Unix systems, whose development required access to selected portions of Windows source code under Windows Interface Source Environment program.. In response, Microsoft released the following statement:
On Thursday, February 12, Microsoft became aware that portions of the Microsoft Windows 2000 and Windows NT 4.0 source code were illegally made available on the Internet. Subsequent investigation has shown this was not the result of any breach of Microsofts corporate network or internal security, nor is it related to Microsofts Shared Source Initiative or its Government Security Program, which enable our customers and partners, as well as governments, to legally access Microsoft source code. Microsoft reaffirms its support for both the Shared Source Initiative and the Government Security Program.
Microsoft continues to work closely with the U.S. Federal Bureau of Investigation and other law enforcement authorities on this matter. Microsoft source code is both copyrighted and protected as a trade secret. As such, it is illegal to post it, make it available to others, download it or use it. Microsoft will take all appropriate legal actions to protect its intellectual property. These actions include communicating both directly and indirectly with those who possess or seek to possess, post, download or share the illegally disclosed source code.
Specifically, Microsoft is sending letters explaining to individuals who have already downloaded the source code that such actions are in violation of the law. Additionally, Microsoft has instituted the use of alerts on several peer-to-peer clients where such illegal sharing of the source code has taken place. These alerts are designed to inform any user who conducts specific searches on these networks to locate and download the source code that such activity is illegal.
Questions about the ongoing investigation should be referred to the FBI.— Microsoft Corporation
Despite the warnings, the archive containing the leaked code spread widely on the file-sharing networks and, even later, on open-source repository websites. On 2004-02-16, an exploit allegedly discovered by an individual studying the leaked source code for certain versions of Microsoft Internet Explorer was reported. On 2015-04-15, a repository containing the leaked NT 4.0 source code was removed from GitHub at Microsoft's request, although other repositories hosting the Windows 2000 source code continued to exist in the same website.
Post NT 4.0 RTM
Service Pack 1 Beta
Service Pack 1
Service Pack 2
Service Pack 3 Beta
Service Pack 3
Service Pack 4 Beta
Service Pack 4
Most NT 5.0 EUR Edition is the modded build as sequel Windows NT 5.0, the $OEM$ Folder has included from past, such as winfile.exe. Shutdown.exe has provided from Windows XP.