Final exam review: osi layers (name & numbering) This layer deals with protocols and services at the user-end level, which means both the osi application layer and the user interact directly with the software application. For example, when you choose to open a webpage in firefox, an application-layer protocol called http (hypertext transfer. Protocol) formats and sends your request from your client"s browser (a software application) to the server. It also formats and sends the web server"s response back to your client"s browser. Application layer separates data into pdus (protocol data units), or discrete amounts of data. Other important protocols and services at this level include, but are not limited to, ftp (file transfer. Protocol), dns (domain name system), snmp (simple network management protocol), and smtp (simple mail transfer protocol). The presentation layer accepts data from the application layer and formats it so that one type of application and host can understand data from another type of application and host.