Aoa meray pyare dosto,
umeed hay sub teek talk hongay mashallah.

Aj aik murtaba phir may kuch naye concepts kay saat hazir howa hon jo kay osi model say mutalik hay.
Osi model kay bare may hum nay basic para ta.our may nay aik example say wazahut ke te.kay office jane say pehlay ap apnay ap ko tayaaar kurtay hay.is tara bulkul data ko network kay opur move kurnay kay kabil bana nay kay leye data ko tayaar kurwana purta hay.pehlay pehlay data ke tayare ka process hum layer seven jo kay Application layer hay say start karengay.to meray dosto,jub hum internet kay opur data send kurtay hein to data kuch steps say guzur kur receiver kay side pur ponchta hay.yane data seven layers say guzur kur tayaar ho kur receiver side pur ponchta hay.right.Hur layer ka apna aik function hota hay.our network kay opur ap cheenk be mare to protocol chaheye hota hay.hur layer kay opur protocol kaam kurtay hein.layers bata te hay kay keya kurna hay.our protocols bata tay hay kay un kamo ko kisay kurna hay.right.
Ab may Application layer say start kurta hoon.
sub say pehlay jub yahoo messenger ke window may Hello may lik kur enter kurtay hay to within seconds ap ka Hello dosray side pur ap kay dost kay screen pur appear ho jata hay.keya howa.ye Hello seven layers say guzur kur ap kay dost kay computer kay screeen pur appear howa hay.right.
ap Msoffice may koye cheeze lektay hay to ye ap actually application layer kay opur kaam kur rahay hein.email waghera lektay hay ap to ye ap application layer kay opur kurtay hay ye kaam.application layer aik interface provide kurte hay ap ko userinterface.Application layer ap kay lekay howay data ko trolle attach kurte hay.our aik ghulaaf chara day te hay.yane apna header attach kurte hay.jis may ye leka hota hay kay age is data kay sat keya kurna hay.right.
to Application layer kay opur ap different applications run kurtay hay.data ke preparation ka process Application layer say start ho jata hay.to application layer ap kay data ko trolly attach kurte hay take network kay opur ap ka data tayze say move ho sake.right.Application layer ap kay lekay hoye data ko passon kur day ta hay presentation layer ko.
ub Presentation layer ka apna kaam hay.ye act kurte hay as a translator kay toor pur.jub ap english lek kur enter kurtay hay to ye to insano ke zoban hay na.computer to is ko nahe samj sukta.compute to binary our hexadecimal ko samuj sukta hay.insano ke zoban decimal our hexadecimal hay.
jub kay computer ke zoban binary our hexadecimal hay.right.hexa decimal ko dono use kurtay hein computers be our humabeings be.right.to presentation layer act kurte ha as a translator .presentation layer kay opur different dictionaries kaam kurte hay.ap ka data jo opur say application layer say ara ha hay wo be different types ka ho sukta hay.is tara presentation layers kay opur different dictionaries ke support hote hay.jub ap simple english text write kurtay hay.to us simple eng text ko coputer kay leye kabile samuj bana nay kay leye presentaion layer kay opur dictionary mawjood hay.different encoding schemes kam kurtay hein presentation layer kay opur.Ascii,Ebcdic waghera.ap kay keyboard may hur eng word kay against aik code generate hota hay.right.ap jub Application layer kay opur Hello lek kur enter kurtay hein.to presentation layer kay pass ye Hello ajata hay.presentaiton layer is Hello ko bits may convert kurnay kay leye jo dictionary use kurte hay wo hay Ascii .right.ub suppose ap jo data exchange kurna chah rahay hay network kay opur wo koy songs hay.gana hay.to is gane ko bits may convert kurnay kaye leye presentaion layer kay opur jo dictionary mawjood hay wohay mp3,wav,wma waghera ke dictionaries mawjood hay jo ap kay songs waghera ko computer readable form may convert kurte hay.ye data ke tayare ka process jare hay
is tara ho suktay hay kay koy video files exchange kur wa rahay hoon.movies waghera.us kay leye be presentaion layer kay opur dictionaries mawjood hay.right
for example avi,mov,mp4,mpeg,flv waghera jo ap kay videos ko convert kurte hay bits may .right.aik bat yaad rake kay presentaion layer kay opur he data(text,audio,video)bits may convert ho jata hay.right.age phir jo physical layer hay wo sirf data ko physical form day day te hay.right.Presentaiton layer encryption ka kam be kurte hay.encryption ka mutlab kay kay apnay data ka asle shakul ko change kurtay hay.take wo hackers waghera say save ho.right.umeed hay yaha tuk ap logo ko samuj achuka hoga.inshallah osi model ka topic jaare hay baqe next time

take care
Allah hafiz
regards
Mujeeb ur rehman khattak