Let's imagine that we have a contract - I give you a bottles of beer (because you love it) and you give me a sensitive anime pictures (because I love it).
- I make a SYN request (offer you a contract of exchange). Say that my bottles will enumerate from 100
- You response with SYN/ACK that you will give me anime pictures and enumerate them from 500. And you accept that you got my offer and now waiting a bottle of beer under number 101
- I tell you ACK that I got your number 500 and waiting for a picture 501. We just started our helpful business
For example I want to give you 10 bottles of deer. I sent them under numbers 101-110. You get them and response "I got bottles and now waiting for bottle 111"
Now you want to send me 20 pictures of girls under numbers 501-520. I will response that got the pictures and waiting for picture 521.
And because of this complicated system we can guarantee that products will delivered. Imagine that you sent me those 20 anime pictures and didn't get a response that I am waiting for 521. You re-send the same 20 pictures some times. If I will not response you will abort the connection and end our contract.



























