computer science

Skype

Skype is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Skype rather than just read about it. In short: Skype ( ) was a proprietary telecommunications application operated by Skype Technologies, an acquired division of Microsoft, best known for IP-based videotelephony, videoconferencing and voice calls. It also had instant messaging, file transfer, debit-based calls to landline and mobile telephones (over traditional telephone networks), and other features.

Key takeaways

Skype belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Skype to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Skype from memory before moving on to harder problems.

Reference excerpt

Skype ( ) was a proprietary telecommunications application operated by Skype Technologies, an acquired division of Microsoft, best known for IP-based videotelephony, videoconferencing and voice calls. It also had instant messaging, file transfer, debit-based calls to landline and mobile telephones (over traditional telephone networks), and other features. It was available on various desktop, mobile, and video game console platforms. Skype was created by Niklas Zennström, Janus Friis, and four Estonian developers, and first released on August 29, 2003. In September 2005, eBay acquired it for $2.6 billion. In September 2009, Silver Lake, Andreessen Horowitz, and the Canada Pension Plan Investment Board bought 65% of Skype for $1.9 billion from eBay, valuing the business at $2.92 billion. In May 2011, Microsoft bought Skype for $8.5 billion and used it to replace its own Windows Live Messenger. As of 2011, most of the development team and 44% of all the division's employees were in Tallinn and Tartu, Estonia. Skype originally featured a hybrid peer-to-peer and client–server system. It became entirely powered by Microsoft-operated supernodes in May 2012; in 2017, it changed from a peer-to-peer service to a centralized Azure-based service. In February 2023, it was used by 36 million people each day. The service was retired on 5 May 2025, and the website now redirects users to Microsoft Teams; however, the Skype Dial Pad remains functional for users with paid services.

Etymology The name for the software was derived from the words "sky" and "peer-to-peer", the latter of which described the software's network architecture. This was then abbreviated to "Skyper"; however, some of the domain names for Skyper were already taken. By dropping the final "r", the title became "Skype", for which domain names were available at the time.

History

Skype was founded in 2003 by Niklas Zennström, from Sweden, and Janus Friis, from Denmark. The software was created by Estonians Ahti Heinla, Priit Kasesalu, Jaan Tallinn, and Toivo Annus. Friis and Annus are credited with the idea of reducing the cost of voice calls by using a P2P protocol like that of Kazaa. An early alpha version was created and tested in spring 2003, and the first public beta version was released on 29 August 2003. In June 2005, Skype entered an agreement with Polish web portal Onet.pl for an integrated offering on the Polish market. On 12 September 2005, eBay Inc. agreed to acquire Luxembourg-based Skype Technologies SA for approximately US$2.5 billion in up-front cash and eBay stock, plus potential performance-based consideration. On 1 September 2009, eBay announced it was selling 65% of Skype to Silver Lake, Andreessen Horowitz, and the Canada Pension Plan Investment Board for US$1.9 billion, valuing Skype at US$2.75 billion. On 14 July 2011, Skype partnered with Comcast to bring its video chat service to Comcast subscribers via HDTV sets. On 17 June 2013, Skype released free video messaging services for Windows, Mac OS, iOS, iPadOS, Android, and BlackBerry. Between 2017 and 2020, Skype collaborated with PayPal to provide a money-send feature, enabling users to transfer funds via the Skype mobile app in the middle of a conversation.

Microsoft acquisition

On 10 May 2011, Microsoft Corporation acquired Skype Communications, S.à r.l for US$8.5 billion. It was incorporated as a division of Microsoft, which acquired all its technologies with the purchase. The acquisition was completed on 13 October 2011. Microsoft began integrating the Skype service with its own products. Along with taking over the development of existing Skype desktop and mobile apps, it developed a dedicated client app for its then-newly released, touch-focused Windows 8 and Windows RT operating systems, which were made available from Windows Store when the then-new OS launched on 26 October 2012. The following year, it became the default messaging app for Windows 8.1, replacing the Windows 8 Messaging app at the time, and was pre-installed on every device that came with or upgraded to 8.1. In a month-long transition from 8 to 30 April 2013, Microsoft discontinued two of its own products in favor of Skype, including its Windows Live Messenger instant messaging service, although Messenger continued to be available in mainland China until October 2014. On 11 November 2014, Microsoft announced that in 2015, its Lync product would be replaced by Skype for Business, combining the features of Lync and the consumer Skype software. Organizations that used it could switch their users between the default Skype for Business interface and the Lync interface.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Skype

Start with the simplest possible case. Write down what Skype claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Skype before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Skype ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Skype

In research: Skype appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Skype in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Skype is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2003 software, 2011 mergers and acquisitions, Android (operating system) software, so understanding it makes those chapters shorter.
In everyday life: Look for Skype outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Skype in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Skype means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Skype out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Skype in simple terms?

Why does Skype matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Skype?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Skype.