Doubt about the information packet in network!

I have a query regarding switches and hubs. I read the following for hubs and switches on a website (http://www.webopedia.com):

In a hub, a frame is passed along or "broadcast" to every one of its ports. It doesn't matter that the frame is only destined for one port. The hub has no way of distinguishing which port a frame should be sent to. Passing it along to every port ensures that it will reach its intended destination.

A switch, however, keeps a record of the MAC addresses of all the devices connected to it. With this information, a switch can identify which system is sitting on which port. So when a frame is received, it knows exactly which port to send it to

So, basically I understand that the difference between switch and hub is that hub multicast every packet even if it is intended for only one node switch only sends the packet to the intended recipient.

Now, my query is:

In this explanation, what is the information packet in the real world. Suppose, there are 4 computers connected to a hub and I am accessing a computer using another computer. I am copying a movie from my computer to that computer. In this case, would the movie be considered packet here?

Please let me know if I am not clear in explaining my query here.

Thanks in advance for clearing my doubt.

Wikipedia has this to say about it: http://en.wikipedia.org/wiki/Packet_(information_technology)

@ Ztrucker - I am already gone through the wikipedia link. I think I am not clear what I want to ask here. I just want to know the information packet in the real world. Suppose, there are 4 computers connected to a hub and I am accessing a computer using another computer. I am copying a movie from my computer to that computer. In this case, would the movie be considered packet here? If yes, then would copying the movie to one computer automatically copy it to other computers as hub multicasts any data packet that comes to it? Please let me know I am not clear enough.

There has to be a way, even with a hub, to differentiate packets so they can reach their required destination. Otherwise you would be getting all kinds of collisions of data being sent and received. There has tp be more to it than what you've stated so far.

Yes, there is something more to it but i don't know what it is. Thats why i asked this query

Each packet is sent with an "address" which I believe to be the MAC address of the receiving computer. Yes, any computer connected to the receiving computer via a hub will have "access" to that packet… but it will not be able to receive it because it will only be able to be received by the appropriate MAC address. A hokey example… the mail system. When a letter is mailed, it has an address of where it goes to. Think of the letter as a packet. It goes into the mail carriers bag with all the other packets. The mail carriers bag is like a hub. All the packets are in there. When the packets get to the main post office…. They are "sorted" into routes. Your packet is sorted into the route where it will be delivered. This is like an upstream switch. In my hokey example… the is another hub as all the packets are transported out to the houses in the delivery mailmans bag. The packets are all together… however the mailman only slips the letter into the slot of the correct addressed home. Only the recipient will get to open it. The switch versus hub issue is mainly about bandwidth. At a hub… traffic from all computers is going everywhich way wherever the data can find space. Think big city gridlock. With a switch, the packet is sent directly to the recipient computer. Think one way streets with no intersecting traffic lights.

Thanks Tomk for the reply!!! I got the difference between routers and switches in the sense what you are saying. You mean to say that hub sends the information packet to every other computer connected to it, however, it is delived only to its intended recipient after checking the MAC address of every recipient with the MAC address of the intended recipient in the frame. Please confirm if I am correct?

I believe that is basically it. The hub isn't really "sending it" to every computer… it's just available on the wire. Only the "correct" computer recognizes it and picks it up.

Thanks tomk!!