Varun Arora

Microsoft Windows is a group of several graphical operating system families, all of which are developed, marketed, and sold by Microsoft. Each family caters to a certain sector of the computing industry. Active Windows families include Windows NT and Windows Embedded; these may encompass subfamilies, e.g. Windows Embedded Compact (Windows CE) or Windows Server. Defunct Windows families include Windows 9x, Windows Mobile and Windows Phone.

Microsoft introduced an operating environment named Windows on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces (GUIs). Microsoft Windows came to dominate the world's personal computer (PC) market with over 90% market share, overtaking Mac OS, which had been introduced in 1984. Apple came to see Windows as an unfair encroachment on their innovation in GUI development as implemented on products such as the Lisa and Macintosh (eventually settled in court in Microsoft's favor in 1993). On PCs, Windows is still the most popular operating system. However, in 2014, Microsoft admitted losing the majority of the overall operating system market to Android, because of the massive growth in sales of Android smartphones. In 2014, the number of Windows devices sold was less than 25% that of Android devices sold. This comparison however may not be fully relevant, as the two operating systems traditionally target different platforms. Still, numbers for server use of Windows (that are comparable to competitors) show one third market share, similar to that for end user use.

As of October 2018, the most recent version of Windows for PCs, tablets, smartphones and embedded devices is Windows 10. The most recent versions for server computers is Windows Server 2019. A specialized version of Windows runs on the Xbox One video game console.

macOS (previously Mac OS X and later OS X, Roman numeral "X" pronounced "ten") is a series of graphical operating systems developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac family of computers. Within the market of desktop, laptop and home computers, and by web usage, it is the second most widely used desktop OS, after Microsoft Windows.

macOS is the second major series of Macintosh operating systems. The first is colloquially called the "classic" Mac OS, which was introduced in 1984, and the final release of which was Mac OS 9 in 1999. The first desktop version, Mac OS X 10.0, was released in March 2001, with its first update, 10.1, arriving later that year. After this, Apple began naming its releases after big cats, which lasted until OS X 10.8 Mountain Lion. Since OS X 10.9 Mavericks, releases have been named after locations in California. Apple shortened the name to "OS X" in 2012 and then changed it to "macOS" in 2016, adopting the nomenclature that they were using for their other operating systems, iOS, watchOS, and tvOS. The latest version is macOS Mojave, which was publicly released in September 2018.

Between 1999 and 2009, Apple sold a separate series of operating systems called Mac OS X Server. The initial version, Mac OS X Server 1.0, was released in 1999 with a user interface similar to Mac OS 8.5. After this, new versions were introduced concurrently with the desktop version of Mac OS X. Beginning with Mac OS X 10.7 Lion, the server functions were made available as a separate package on the Mac App Store.

macOS is based on technologies developed between 1985 and 1997 at NeXT, a company that Apple co-founder Steve Jobs created after leaving the company. The "X" in Mac OS X and OS X is the Roman numeral for the number 10 and is pronounced as such. The X was a prominent part of the operating system's brand identity and marketing in its early years, but gradually receded in prominence since the release of Snow Leopard in 2009. UNIX 03 certification was achieved for the Intel version of Mac OS X 10.5 Leopard and all releases from Mac OS X 10.6 Snow Leopard up to the current version also have UNIX 03 certification. macOS shares its Unix-based core, named Darwin, and many of its frameworks with iOS, tvOS and watchOS. A heavily modified version of Mac OS X 10.4 Tiger was used for the first-generation Apple TV.

Releases of Mac OS X from 1999 to 2005 ran on the PowerPC-based Macs of that period. After Apple announced that they were switching to Intel CPUs from 2006 onwards, versions were released for 32-bit and 64-bit Intel-based Macs. Versions from Mac OS X 10.7 Lion (2011) run exclusively on 64-bit Intel CPUs, in contrast to the ARM architecture used on iOS and watchOS devices, and do not support PowerPC applications.

Originally developed as Facebook Chat in 2008, the company revamped its messaging service in 2010, and subsequently released standalone iOS and AndroidAndroid apps in August 2011. Over the years, FacebookFacebook has released new apps on a variety of different operating systems, launched a dedicated website interface, and separated the messaging functionality from the main Facebook app, requiring users to use the web interface or download one of the standalone apps. Users can send messages and exchange photos, videos, stickers, audio, and files, as well as react to other users' messages and interact with bots. The service also supports voice and video calling. The standalone apps support using multiple accounts, conversations with optional end-to-end encryption, and playing games.

This interoperability is just one of many features of the new Messenger. All messages will also be end-to-end encrypted, which is part of Facebook's recent privacy-focused mantra. Sharma said that the inter-app messaging will work similar to how people make calls on phones today. You don't need to know if your friend is on VerizonVerizon or T-MobileT-Mobile, you can just call them. It'll be the same on any of Facebook's messaging services -- just say you'll want to talk to your friend, and that message will get to him or her on whatever service they use.

It's unclear just yet when this will roll out to users. ZuckerbergZuckerberg said it could take quite some time, which might mean next year or later.

At F8 2019, Facebook also announced that it would bring Messenger, its popular messaging client, to MacMac and WindowsWindows.

The desktop version of Messenger will include audio calls, group video calls, and other features that are familiar from the mobile version. It's likely based on Messenger.com, a webweb-based version of Facebook Messenger that has long been a faster alternative to using Messenger from Facebook's web interface.

A BitTorrent tracker is a special type of server that assists in the communication between peers using the BitTorrent protocol. In peer-to-peer file sharing, a software client on an end-user PC requests a file, and portions of the requested file residing on peer machines are sent to the client, and then reassembled into a full copy of the requested file. The "tracker" server keeps track of where file copies reside on peer machines, which ones are available at time of the client request, and helps coordinate efficient transmission and reassembly of the copied file. Clients that have already begun downloading a file communicate with the tracker periodically to negotiate faster file transfer with new peers, and provide network performance statistics; however, after the initial peer-to-peer file download is started, peer-to-peer communication can continue without the connection to a tracker. Since the creation of the distributed hash table (DHT) method for "Trackerless" torrents, BitTorrent trackers have largely become redundant; however, they are still often included with torrents to improve the speed of peer discovery.

Demonoid was a BitTorrent trackerBitTorrent tracker and website that included file-sharing related discussion forums and a searchable index for the tracker. The site underwent intermittent periods of extended downtime due to the occasional need to move the server, generally caused by cancellation of ISP service due to local political pressure. There are reports of its founder Deimos passing away in September 2018 and the future of the site is currently uncertain.

Demonoid was a BitTorrent tracker and website that included file-sharing related discussion forums and a searchable index for the tracker. The site underwent intermittent periods of extended downtime due to the occasional need to move the server, generally caused by cancellation of ISP service due to local political pressure. There are reports of its founder Deimos passing away in September 2018 and the future of the site is currently uncertain.

Originally developed as Facebook Chat in 2008, the company revamped its messaging service in 2010, and subsequently released standalone iOS and Android apps in August 2011. Over the years, Facebook has released new apps on a variety of different operating systems, launched a dedicated website interface, and separated the messaging functionality from the main Facebook app, requiring users to use the web interface or download one of the standalone apps. Users can send messages and exchange photos, videos, stickers, audio, and files, as well as react to other users' messages and interact with bots. The service also supports voice and video calling. The standalone apps support using multiple accounts, conversations with optional end-to-end encryption, and playing games.

At F8 2019, Messenger's head of consumer product Asha Sharma announced that in the future, users will soon be able to send messages across Facebook's three different messaging platforms: Messenger, Instagram and WhatsApp.

This interoperability is just one of many features of the new Messenger. All messages will also be end-to-end encrypted, which is part of Facebook's recent privacy-focused mantra. Sharma said that the inter-app messaging will work similar to how people make calls on phones today. You don't need to know if your friend is on Verizon or T-Mobile, you can just call them. It'll be the same on any of Facebook's messaging services -- just say you'll want to talk to your friend, and that message will get to him or her on whatever service they use.

It's unclear just yet when this will roll out to users. Zuckerberg said it could take quite some time, which might mean next year or later.

At F8 2019, Facebook also announced that it would bring Messenger, its popular messaging client, to Mac and Windows.

The desktop version of Messenger will include audio calls, group video calls, and other features that are familiar from the mobile version. It's likely based on Messenger.com, a web-based version of Facebook Messenger that has long been a faster alternative to using Messenger from Facebook's web interface.