hello and welcome to this video i'm going to be talking about ad-hoc networks and what they are and why they are used and looking in particular at tethering and personal hotspots so before we start talking about adult networks in particular let's focus on what a network is more generally so network is the connections between devices which enable resources and data to be shared between those devices so because you are on youtube watching this video you're on a network possibly your home network which might be connected to the internet maybe you are at school maybe you're on your phone maybe you're using a personal hotspot if you connect wireless headphones to your phone that's also a network any connection between devices which enables some data to be shared between them so here is a relatively typical diagram of what a network might look like this is what we would call a bus network we've got a big white in the middle which is what we call the bus with computers connected to it including a printer and a server a server being a really powerful computer now perhaps stating the obvious a little bit but networks are important because they make communication usually easier and faster so going back before networks were really around if you say had an office in london and another office in newcastle you'd have to communicate via letter or by someone going between the two places via car or via train whereas now you can send an email over network and it's much quicker and faster also networks enable us to make use of our resources more efficiently in many cases so in this network here we've got a printer we've got a server and on our workstations we'll have some data and some software all of those could be resources and having a network means you can share these more easily so here i've got one printer connected to the network and so every computer can use the printer we don't need a separate printer for every computer which is not an efficient use of resources now an issue that can arise in most i'll say normal networks the ones you'll find at home at school at work is that they can be quite fixed in how they are arranged they're set up in a very particular way especially for the wired parts and so if you want to make any changes they're going to be quite difficult now mr mature will strike fear into any network administrator all these wires crisscrossing now i hope your school your home does not look like this but the point remains if you want to move one of your devices around maybe you want to change where your printer is if you want to move the server it's not easy so if you want to move it for 10 minutes it's just not worth the effort to have to reroute all the wires and drill through a wall and all these sort of things even in a home which is hopefully more reasonable you've got certain ports in the wall where you plug in your router plug in your tv and it connects to the wider network now they're not everywhere right you probably don't have one of these ports in every single room of your house there might be one room in your house which has these ports and so your choice of where to put your router is not really a choice i suppose you're kind of forced to put it in a certain position and that lack of flexibility is okay most of the time but if you want to make a small change especially a temporary change it's very hard to have to re-route and change the layout of your network let's say it's a beautiful sunny day and you want to go and work in your garden and your wireless router doesn't have a range big enough for you to to work in your garden on your laptop well the issue is you can't easily just take your router outside because it's got a wire it's connected to the wall it's not designed to just be moved around it's meant to sit in one place in a fixed arrangement and that lack of flexibility can be a problem and is why we have ad hoc networks now if ad hoc as a phrase sounds a bit odd it's because it is it comes from latin and it just means to this in latin so it tends to be where you're using something for a very specific purpose and as a phrase you hear it quite a lot in work context it refers to things which happen fairly spontaneously so without planning for instance meetings can be ad hoc your teachers might meet once a week every let's say monday morning to discuss plans that might be in the schedule every single week but sometimes things come up during the week and so ad hoc meetings may be called just happens spontaneously without much planning now ad hoc networks are similar in nature in that they're not really long-term solutions the networks which can be set up quite easily and can be flexibly changed unlike most normal networks and they often set up for only a short period of time so they're temporary so let's say in your house you've got your laptop and you've got your wireless router well your router is going to be connected to the internet via that port in your wall and it'll produce a wireless signal using radio waves which your laptop can pick up that's what we call a traditional network you can't easily change where your router is you can't move it around like i've said now let's say your internet goes down you get this awful message which no one likes to see well what could you do you could set up a ad hoc network on your phone because your phone or many phones have got a feature where you can set up a personal hotspot so personal hotspot is a very short-term network you create just to enable you to connect usually for a short period of time so you can connect wirelessly to your phone and it would use your mobile network instead of your home network giving you internet on your computer so a personal hotspot is an example of an ad hold network you can set it up very quickly without much trouble can be changed very easily and it's usually not lasting for a very long time