OSI Model

 

-application layer that what you interface with it, as you a backend or  frontend engneering like http protocol here it responseable to preparing the payload data all data i have to send (get req , header ,... ) then i have a chunk of data 

-presentation layer  : serializtion and  encrypting and decrypting 

-session layer maintains the connection and It distinguishes between the connections it  makes with different devices 

-transport layer :  deal with application port  ,what the port that where you go ,what the port the you had come from (why you asking becauuse we need it for response from server )  and those things add , and  the chunk become a segments  and add sequence numbers to make they able to sort like they were

-then network :  ip protocol deal with ip  ,add destination ip adress and source ip adress to the segments and we call it packets 

-the second layer data link  : it add destination mac adress and sources mac adress to packets and we call that frames

we use mac adress for connaction between device because it is unique no two device have the same mac adress )

how i find the destination mac adress when i have destination ip adress i do ARP ( ADRESS RESOLUTION PROTOCOL )

-then pythsical layer :  take the frame and string it a bunch of bit 

then it is shoves into meduim (ethernet , fiber ,... we don't really care) and transmit it