Skype

Skype ( /skaIp/) is a software program that uses the Internet to make telephone calls (using a technology called Voice over Internet Protocol (VoIP). It was created in 2003 by the Swedish and Danish Niklas Zennstrom and Janus Friis. A company currently owns it in Luxembourg called Skype Technologies S.A.R.L, which since 2011 has been part of Microsoft. (From 2005 to 2011, Skype was owned by eBay.)
The Skype program works on computers with Microsoft Windows, macOS and Linux. It is available as a mobile app for different platforms, including iOS and Android. Using VoIP to make calls is very cheap to call another phone. It does not cost money to call another Skype user. Every Skype user has a unique name to which other users can find and talk. Skype also has additional features such as video calls and multiple members in a conversation. In the chat, you can also find a selection of various emojis available.
History of Skype
September 2002: investment from Draper Investment Company.
April 2003: Skype.com and Skype.net domain names registered.
August 2003: First public beta version released.
September 2005: Skype for talking is banned in South China.
October 2005: eBay bought Skype.
December 2005: videotelephony introduced.
April 2006: 100 million users.
October 2006: Skype 2.0 for Mac is released, the first full release of Skype with video for Macintosh.
December 2006: Skype announces a new pricing structure as of January 18, 2007, with connection fees for all SkypeOut calls* March 2007: Skype 3.1 is released, adding some new features, including Skype Find and Skype Prime. Skype also released a 3.2 beta with a new feature called Send Money which allows users to send money via PayPal from one Skype user to another.
August 2007: Skype 3.5 for Windows released with additions such as inclusion of video content in chat, call transfer to another person or a group,
August 15, 2007: Skype 2.7.0.49 (beta) for Mac OS X released adding availability of contacts in the Mac Address Book to the Skype contact list, auto redial, contact groups, public chat creation, and an in-window volume slider to the call window.
August 16 / August 17, 2007: Skype users unable to connect to full Skype network in many countries
November 2007: Skype users in London who use the 020 city code lost the phone numbers that connected to their Skype accounts after December 2007.
Security
Skype has an encryption system for security. This system cannot be turned on or off. Skype provides an uncontrolled registration system for users. People can use the system safely without revealing their real-life identity to other users of the system, but there is no way to know that the person they communicate with is the one they say they are.
Criticism
Skype has many points of critisism, such as:
Skype clients can become supernodes. These supernodes hold together the peer-to-peer network. It can use a big quantity of bandwidth. For this reason, some universities have banned the use of Skype.
Significant use of obfuscated code
Keeps chatting on the network
Blind trust in anything else speaking Skype
Ability to build a parallel Skype network
Lack of privacy (Skype has the keys to decrypt calls or sessions)
Heap overflow in Skype
Skype makes it hard to enforce a (corporate) security policy
"No way to know if there is/will be a backdoor"
Users of Skype on Mac OS X have poor audio quality when connecting to Mac/Mobile clients
Bugs and delays in the Linux version
Other websites
Official Skype website
Planetskype website
Portable Skype (Windows)
2003 establishments
File sharing
Video chat
Telephone