computer science

VCard

VCard 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 VCard rather than just read about it. In short: vCard, also known as VCF ("Virtual Contact File"), is a file format standard for electronic business cards. vCards can be attached to e-mail messages, sent via Multimedia Messaging Service (MMS), on the World Wide Web, instant messaging, NFC or through QR code. They can contain name and address information, phone numbers, e-mail addresses, URLs, logos, photographs, and audio clips. vCard is used as a data interchang…

Key takeaways

VCard 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 VCard to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of VCard from memory before moving on to harder problems.

Reference excerpt

vCard, also known as VCF ("Virtual Contact File"), is a file format standard for electronic business cards. vCards can be attached to e-mail messages, sent via Multimedia Messaging Service (MMS), on the World Wide Web, instant messaging, NFC or through QR code. They can contain name and address information, phone numbers, e-mail addresses, URLs, logos, photographs, and audio clips. vCard is used as a data interchange format in smartphone contacts, personal digital assistants (PDAs), personal information managers (PIMs) and customer relationship management systems (CRMs). To accomplish these data interchange applications, other "vCard variants" have been used and proposed as "variant standards", each for its specific niche: XML representation, JSON representation, or web pages.

Overview The standard Internet media type (MIME type) for a vCard has varied with each version of the specification. vCards can be embedded in web pages. RDFa with the vCard Ontology can be used in HTML and various XML-family languages, e.g. SVG, MathML.

RFC 9554 Extensions RFC 9554 defines several new vCard properties, namely CREATED, GRAMGENDER, LANGUAGE, PRONOUNS, and SOCIALPROFILE, and some new parameters for existing properties. It also updated the ADR and N properties to support more detailed addresses and secondary surnames respectively. The extension exists to align the same set of features between the JSContact and vCard formats.

Related formats jCard, "The JSON Format for vCard" is a standard proposal of 2014 in RFC 7095. RFC 7095 describes a lossless method of representing vCard instances in JSON, using arrays of sequence-dependent tag–value pairs. jCard has been incorporated into several other protocols, including RDAP, the Protocol to Access White Space Databases (PAWS, described in RFC 7545), and SIP, which (via RFC 8688) uses it to provide contact information for the operator of an intermediary which has rejected a call. hCard is a microformat that allows a vCard to be embedded inside an HTML page. It makes use of CSS class names to identify each vCard property. Normal HTML markup and CSS styling can be used alongside the hCard class names without affecting the webpage's ability to be parsed by a hCard parser. h-card is the microformats2 update to hCard. MeCard is a variation of vCard made by NTT DoCoMo for smartphones using QR codes. It uses a very similar syntax, but in a more consolidated way as the storage space on QR codes is limited. It's also limited in the amount of data that can be stored, not just by the standard but the size of QR codes.

Example An example of a simple vCard:

BEGIN:VCARD VERSION:4.0 FN:Simon Perreault N:Perreault;Simon;;;ing. jr,M.Sc. BDAY:--0203 GENDER:M EMAIL;TYPE=work:simon.perreault@viagenie.ca END:VCARD This is the vCard for "Simon Perreault" (the author of RFC 6350), with his birthday (omitting the year), email address and gender.

Properties vCard defines the following property types. All vCards begin with BEGIN:VCARD and end with END:VCARD. All vCards must contain the VERSION property, which specifies the vCard version. VERSION must come immediately after BEGIN, except in the vCard 2.1 and 3.0 standards, which allows it to be anywhere in the vCard. Otherwise, properties can be defined in any order.

See also CardDAV FOAF (ontology) Geo URI scheme

Notes

References

External links vCard 4.0 at its developer CalConnect RFC 9554 describing extensions to vCard version 4 RFC 6350 describing the vCard format version 4 RFC 2426 describing the vCard format version 3 vCard and vCalendar (old versions) from the Internet Mail Consortium in the Internet Archive

Worked examples

Example 1 — a first encounter with VCard

Start with the simplest possible case. Write down what VCard 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 VCard 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 VCard 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 VCard

In research: VCard 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 VCard 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: VCard is common in secondary-school and first-year university syllabi. It links to neighbouring topics Business cards, Computer file formats, Internet Standards, so understanding it makes those chapters shorter.
In everyday life: Look for VCard 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 VCard in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what VCard 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 VCard out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is VCard in simple terms?

Why does VCard 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 VCard?

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 VCard.