olemus
omanduslik (Whatsapp Inc/Facebook Inc) kiirsidesüsteem (eeskätt mobiilseadmetel) tekst-, pilt-, video-, häälsõnumite ja -dokumentide edastuseks (alates 2009); kasutab mobiiltelefoninumbreid tasuta, on mitmeplatvormiline; on populaarseim sõnumsiderakendus, üle miljardi kasutaja (2016), peamine SMS konkurent
Wiktionary:
an instant messaging service founded in 2009 and acquired by Facebook in 2014

ülevaateid
https://en.wikipedia.org/wiki/WhatsApp
https://www.peoplefirstinfo.org.uk/media/mrijxiox/how-to-use-whatsapp.pdf
https://www.ic.unicamp.br/~oliveira/doc/MHCI2013_Whats-up-with-whatsapp.pdf

turvalisus
https://www.wired.com/story/whatsapp-security-flaws-encryption-group-chats/
https://www.makeuseof.com/tag/4-security-threats-whatsapp-users-need-know/
https://foundation.mozilla.org/en/privacynotincluded/whatsapp/
https://en.wikipedia.org/wiki/Reception_and_criticism_of_WhatsApp_security_and_privacy_features