Application Layer

The name of layer refers as "Application layer". It means this layer works on application or software. It does not means it browser run on this layer, it only execute the program not display. For example if we click some icon name My Document it first execute the command you give and after that display the window My Document. The difference between upper example and application layer is it only execute the command but not display. It provide interfaces between operating system and software and also communication data like messages,file.
It is also called End User Layer because it show what was sent and creates what to be sent. It contains protocols that help sharing resources in the network also provide protocols that uses for remote printer sharing. Some of protocols provide remote file access network management and directory services.
Protocols are executed on this layer. FTP,DNS,DHCP, TELNET,HTTP/HTTPS etc are protocols executed on this layer. We little bit discuss these protocols in this post explanation of these protocols discuss later on other post.
FTP : Ftp stands for "File transfer protocols".Ftp is client server protocol, it transfer file from one computer to another computer client and server. Ftp client server protocol used to transfer and be connected to client computer. Ftp client built on the site of  modern consumer and connection between various user. Simple example when we copy or paste any thing Ftp works there.
DNS (Domain Name Server):DNS stand for Domain Name System. It work on URL back end. Protocols are used for mapping the required URL.For example www.Yahoo.com DNS is mapping 149.171.1.221. IP address of Yahoo.com. In simple words it translate URL name to IP address.All internet is base on IP adresses not URL cause their alphabetic name.
DHCP: DHCP stands for "Dynamic Host Configuration Protocol". This protocol automates IP address to devices, that means this protocol automatically provide an address against each device that help all devices to perform on internet.
Telnet: Telnet is a protocols that provide facility to the user to have Remote Access of the PC's. It provide facility to use one and also get access the other computer on different location that can be in the network or between networks or networks at far location. A software name TeamViewer is example of Telnet protocol.To access router to router require Telnet and pc to pc access use Teamviewer.
HTTP/HTTPS: First we see the basic different in HTTP and HTTPS is that HTTP is insecure and HTTPS is secure in sense of hacking.
SMTP:SMTP stand for Simple Mail Transfer Protocol. This protocols used when an email received from email server or delivered from one email server to another email server.

The above fig show how application layer work .A data with header that by Presentation layer and then executed by Application layer.  In left fig a data is send by application layer with adding header to presentation layer and on right fig. show how data received from presentation layer and executed. This header is adding or executed by application layer.