Vcards are electronic business card, most programs and devices can export and import vcards using *.vcf (it does not mean visit card file, it means ) files. Unfortunately vcards are not well defined and therefore the interoperability often does not give the expected result since the different implementation interpret the vcards differently. An xml implementation of vcards http://tools.ietf.org/html/rfc6351 (filenames *.xml ) should clarify this situation. Even though the standardization makes big process and talking about xml and vcard version 4, year 2012 devices as the Samsung Galaxy S3 export in very badly formatted vcard version 2.1 format.
Except for blocks of embedded coded data, vcard files contain lines of text holding an vcard element:
<tag><;optional parameters>
:<value><;optional additional value>
Basically the : character splits identifiers from values and the identifiers and values might be an array separated with the ; character.
Vcards start with BEGIN:VCARD and end with END:VCARD. This way multiple Vcards can be added to a single file. Vcard has been grown historically and had and still has its troubles. It got improved and therefore is is mandatory and useful to have at the second line the vcard version.