olemus
kõrgeim kiht võrgumudelites:
OSI mudelis 7. kiht, TCP/IP-mudelis 4. kiht ( ≈ OSI kihid 5+6+7);
annab rakendusprogrammidele teenuseid infovahetuseks teiste rakendusprogrammidega, seega annab teenuseid lõppkasutajale; määrab selleks protokollid ja meetodid
= an abstraction layer that specifies the shared protocols and interface methods used by hosts in a communications network
ISO/IEC 2382-26:
kiht, mis annab rakendusprotsessidele vahendid pääsuks OSI keskkonda ja andmevahetuseks ning sisaldab rakenduskeskseid protokolle, mille abil need protsessid suhtlevad
= layer that provides means for the application processes to access the OSI environment
Note 1.This layer provides means for the application processes to exchange data and it contains the application-oriented protocols by which these processes communicate.

protokolle
DNS, HTTP, FTP, SMTP, Telnet

ülevaateid
https://www.youtube.com/watch?v=wA9E85b4r5U
https://www.youtube.com/watch?v=MQUi9NMMO5Y
https://en.wikipedia.org/wiki/Application_layer
https://www.mi.fu-berlin.de/inf/groups/ag-tech/teaching/2011-12_WS/L_19531_Telematics/09_Application_Layer.pdf
https://courses.cs.washington.edu/courses/cse461/17au/lectures/02-Applications-1-DNS.pdf
https://www.cs.huji.ac.il/course/2002/com1/book/chapter2.pdf

turvalisus
https://securityboulevard.com/2020/06/eye-on-the-end-user-application-layer-security/
http://ijcset.net/docs/Volumes/volume2issue6/ijcset2012020605.pdf
http://www.cse.yorku.ca/SecRAY/AppLayerSecurity_Andrade.pdf
https://www.astesj.com/publications/ASTESJ_040131.pdf