First of all, what I am going to do is, because I can see very beautiful faces, girls, and of course, handsome boys. Can I take a photo of you guys? Okay, the first thing I'm going to do is take a photo of you guys, okay? Okay, guys say "cheese", everybody. Good. Fantastic. Yes. So you know what I'm going to do with the photo? I am going to send this photo to the one I like the most. The one I love the most. So can you guess who it is? Who is it? Your wife. Definitely not. Come on, we've been married for 20 years now, right? So how can it be after 20 years? Not my kids, not my wife, it should be my...? Kids. No. Not for the kids. Kids I meet them every day. Nothing exciting, right? So who it should be? Don't tell my wife that's my girlfriends, okay? So I'm going to send this photo to my girlfriend, alright? So that's what I'm going to do. Don't tell my wife, otherwise, I'd be in trouble. I may not be able to go home tonight, okay? Alright. So what I'm going to do is, the photo I have taken, I'm going to, this is my Percy's photo, right? Percy's photo. I'm going to send it to my girlfriends. My girlfriend's computer is somewhere here. Is that right? Yes. So what I'm going to do is, I'm going to attach the nice photo of you guys, I'm going to send it to my girlfriend, right? So the first thing that happen is this, the photo goes out of the computer here. Is that right? It goes out of your computer. So there's a place that you guys connect your cable to your computer, right? So you have a cable. So how do you call that place? How do you call it? Port. Yes, it is a port, but the correct word is we call it as network interface card. So there's something called network interface card, we connect that cable. So then we connect the cable, and then what I do is I attach your photo to the email client, whatever the email we have it, I click the send button, right? So once I do that, it goes out of my computer. Does it go directly to my girlfriend's computer? Where does it go first? Server. Yes, you should ask me what is my email address, right? So my email address is percy@, of course, ust.hk. So it goes to where? To? Server, UST mail server, right? So UST mail server. And then it's going to be the server, mail server. So then, after that, where does it go? The packets go all the way to another server. Yes. Does it go to my girlfriend's computer directly from there? So where does it go to next? Go to her email server. I'm not going to tell you guys her email address, but her email address, assume that Yahoo.com. So it goes to the Yahoo, right? Email server. It's going to be there until she opens the Yahoo mail client. So once she open the Yahoo mail client, this email can be downloaded to her computer and of course, she can see you guys' photos here. Is that right? That's how it is. First of all, why we'd need networking? Networking is needed for us to receive, sending, receiving communication, information. That's why we need a network. The next question I'm asking you is this, I send a photo, so it goes out of my computer, does it go like a photo? No. No. Then what happen? Converts. Sorry. Everything converts to 0s and 1s. Exactly. So whatever that's going through the network is combination of 1s and 0s, right? So everything no matter whether we're sending a video stream, whether we're sending a photo, whatever it is, when it goes, before it goes out of the computer, everything has to be converted to 1s and 0s. The process of converting to 1s and 0s is called encapsulation. I'm going to just go through with you guys what's the process here. But at same time, one of the most important thing is this. It goes out of this computer. I don't want it to go. My wife's computer is somewhere here, right? I don't want it to go to my wife's computer. I really want it to go to my girlfriend's computer. So the most important thing is when it goes out, it should find the correct path no matter where my girlfriend is, right? So its path determination is extremely important. When we send out from the sender to the receiver, it goes to the destination. It's very important here. So that is important. So these are the things that we basically need to understand. So when it goes out of this, my computer, how to find the path to the destination. That's something also we have to understand. At the same time, what process happens within my computer to convert the photos to combination of 1s and 0s? So these are the important things.
