eli5: What is bandwidth?
In: 48
You want some water. I could get it from the source with a eye dropper or with a bucket. The eyedropper or bucket is the bandwidth capacity – the amount of stuff I can transfer in one trip.
Imagine a thin coffee stirring straw. Now imagine one of those big fat straws you can drink a milkshake through.
Bandwidth is the straw. The liquid you can get through it is data. And if a chocolate chip clogs up your milkshake straw, well that’s a chocolate chip.
It is how wide the band is :-).
In radio it is how wide of a frequency range you have. It can be very narrow and it can be very wide. This is closely regulated by the FCC and you need to have a license to operate in certain bands.
In data it is how many bits can I transfer, the more the better. In computing we are a little less literal about bandwidth, in radio and wifi we are literally talking about frequency bands.
These ideas combine in interesting way. Lets say I have a fiber optic connection between two sites using the typical laser RF. I can get a maximum *bandwidth* in the 1310 or 850 nanometer fiber optic cable. But, lets say I literally divide up the light frequencies in the dense waves (this means something but it isn’t important here) and I send on wave 1 and receive on wave 2. I have literally doubled my bandwidth because I am now working on two different bands.
Mobile carriers want more *bandwidth* (see the controversy about ILS landing radios) because each mobile must have a specific band to get phone calls on, otherwise more than one cell phone will ring when you call one person! You can use filter circuits all you want but when it comes right down to it if you want more mobile devices you need more bands to put the phones on.
Water is always the best analogy.
The internet works on sending chunks of data called packets. These are sent in speeds of megabits per second (mbps) A megabit of packets is how much data and per second is how fast. Basically, bandwidth is how many packets and how quickly.
Using the water analogy a house might have a small diameter pipe with slow moving water through it. If you’ve ever been in a shower with low water pressure that’s the water equivalent to “low bandwidth.”
Another house might have a large diameter pipe and get a lot of water really quickly. That’s high bandwidth.
Another water comparison: Niagara Falls is high bandwidth whereas the tap in your bathroom is low.
Relating back to data when internet companies sell you internet connections they control how big (virtually, not literally) the diameter of your “pipe” is. Pay more get a bigger pipe and more bandwidth.
Explain like you’re five? You and your friends all need to go back into the school after recess. What would be faster? If you had to go through the door one-by-one? Or if the door was big enough so you could all go inside at the same time?
Bandwidth is the size of the door…
Bandwidth is the amount of data that can be sent from one computer to the other per second. Latency is how fast that data can go between one computer to the other.
Bandwidth nowadays tends to refer to the aggregation of multiple radio frequencies into a single usable communications channel.
Your typical home ‘fibre’ internet connection will use approximately 4096 different radio frequencies combined to give your total speed.
Most of these frequencies are allocated to your download speed and just a handful of them are allocated to your upload speed.
Each one of those frequencies is like a miniature telephone call between your modem and the wholesalers modem. They are both constantly checking the volume and clarity of each call and adjusting each one up and down as necessary.
Your internet connection, in many cases, is simply radio frequency over copper.
In the UK, the frequency for Radio 4 coincides with one of the 4096 calls your modem is managing. Instead of allowing your modem to constantly battle with that frequency, it is generally mapped out of your internet profile so that particular call is never made.
You sacrifice a tiny amount of ‘bandwidth’ and thus overall throughput/speed as a result.
Bandwidth as defined in signal processing:
It’s the frequency range a system can use. The more frequencies, the higher the bandwidth. As an analogy, compare a [Low Bandwidth](https://d1aeri3ty3izns.cloudfront.net/media/31/316735/1200/preview.jpg) vs [High Bandwidth](https://keyboardkraze.com/wp-content/uploads/2020/03/Organs.jpg.webp) keyboard.
Bandwidth as defined in data transfer:
It’s the total amount of data (or the number of data packets) that can be sent in a given time. The more data/packets, the higher the bandwidth. Again, to use an analogy, if data packets were bullets, a [musket](https://www.youtube.com/watch?v=SJMbxZ1k9NQ) would be low bandwidth, an [M134](https://www.youtube.com/watch?v=vfRpiem7yps) high bandwidth.
It depends on the band, and the space available; some smaller ensembles are only 12ft, but a big band can be 25ft+
Also, the band width can be bigger or smaller if they are on tour, it depends what can fit in their van, and how far from home they are.
It is the number of lanes on your internet highway. More lanes, more cars (data packets) can go at once.
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