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Packets, Protocols and Privacy.html

Here's another way to look at it.

Most of us think that, as long as the information shows up on our screen, that's all we need to worry about. But it's not, even if your concern is with the wider world of social, political, or business concerns. The technology matters because, as we have already seen, it changes us. There are two technologies that we'll spend a little time on. In a way, most of what happens on the internet can be categorized in one of these two technologies. The one is data transfer. The other is database.

Both of these technologies are content agnostic. They don't know and don't care what is contained in the data they deal with. But what they do with the data has consequences, particularly when it comes to what information you ultimately have access to whether or not that access is censored.

We've looked at the mechanics behind preparing data for transport. Here's a summary.

Most pieces of information you want to send or receive on the internet are two big to send in a single chunk.  So when you hit the send button, the first thing that happens is the breaking down of the data in the information into chunks of a manageable size. Anticipating that such a chunk with eventually be transported, You may remember that we called this chuck of data segment. You can also call it a payload. When the payload arrives, it is reassembled into the information that was originally sent.

Before the payload can be transported, though, it needs to be packaged properly and it's this package that compromises most of the data on the internet. It's a little known fact that we never see the majority of data we generate.  The packaging and the payload together are called the packet. Here's how the packet is constructed.

When two computers want to talk to each other, they have to know some things about each other. For obvious reasons, they have to know each other's address. They also have to know some other things like: How will it recognize a packet as belonging to a specific piece of information? How does reconstruct the payload into the original piece of information if they  arrive in a different order than when it was sent?  Will the final product be a photograph or a drawing or text or sound? What should happen if some of the pieces don't arrive?

These rules of understanding are called the protocol. Each computer in the transfer process has to have the same protocol installed so it has something to reference in order to make sense of the packets as they arrive.

Here's our email example again. If you want to send an email, your email application will use a protocol like SMTP (Simple Mail Transfer Protocol). Why? Because the application on both ends have to read and write the same way. It would be no good for someone to write a letter in Greek only to have an English speaker try to read it. They both have to agree on how the email will be transported. It would also be a bad idea for one end to send an envelope and the other to expect a box, So they agree on TCP (Transfer Control Protocol). The data organized using SMTP plus the Transport Header with all the TCP information is called a Segment.  The segment includes things like Port Numbers. You'll hear about  Ports in the video. And it includes a length of time a segment is allowed to rattle around on the internet if it gets lost before everyone gives up on it (called Time to Live). Then they agree how it's all going to be addressed and sent. For this, they decide to use IP (Internet Protocol). IP addresses have two parts: a network part, that identifies the collection of computers that the sender and the destination are part of, and the host address which identifies the actually machine.  All this combined is called a packet. Finally, it's all prepared for the media on which it will travel such as Ethernet on copper wire or wireless (802.11g for example). This final preparation is called a Frame.

Remember that data transfer is content agnostic. It doesn't care about what is in the payload of a packet. But lots of other people do and these technical details are the backbone of two of the most significant issues in Information Technology today: security and surveillance.