This is a simple Google site, cached in Google's CDNs so it's as fast as possible.
It contains information and language to cut through the jargon that is not just confusing but misleading.
Latency
Jitter
Speed (aka Bandwidth)
General definitions of wISP, fISP, etc.
The truth about Speed Tests
delivery methods such as wireless, copper, fiber, satellite.
The delay from when a request is sent to when it's received.
Examples:
clicking on a link and getting the page involes a number of requests to be sent, the latency or delay from each request is a major factor in how fast a web page feels.
when talking on the phone, the delay from when you talk to when the other party hears you. The delay you experience on a cell phone call from far away for example, that's latency.
'lagging out' in a game when your commands take to long to arrive.
Bad latency is often misunderstood as 'slow internet'. A misguided solution is often to buy more internet speed.
Latency can be thought of as the quickness, how quickly you can drive from point A to point B. Latency is variable, like the traffic on the road. When there is congestion you can get slowed down a lot.
The CAPACITY of an internet connection. Frankly, this is a terribly misunderstood term. Your internet capacity or bandwidth is the guard rails imposed by your provider per your service plan. It's only part of how 'quick' a web page loads or your Netflix finishes buffering.
It's the how much can you have if you want it, not how quickly it travels.
Netflix for example, it needs about 3Mbps to send you a standard resolution video. Netflix would like to buffer about 10 seconds of video so if you have a 3Mbps connection, you'll either get a worse stream, or it'll take you 10 seconds before it starts playing. If you have a 300Mbps connection, you can potentially get all the video essentially instantly. If you have a 30Mbps connection then you also get that essentially instantly because 3Mbps * 10 seconds is 30Mbps, you can get it all in 1 second.
So in practical terms, you need enough speed for how you use the connection, and really not much more. If you stream netflix on 1 TV and browse facebook, a 30Mbps internet service is very practical for you. Then the other pieces of the puzzle matter, namely Latency. You want facebook to load quickly and things to happen as you click them.
Where you need or want more and more speed is when you are doing even higher definition streaming, big downloads like game updates, or when you need to download big files for work. Netflix for example needs about 12Mbps for a 4K stream so your 30Mbps service will still work. Netflix will start playing these streams with about 5 seconds of buffer so you need about 2 seconds to start playing. That's 12Mbps*5=60Mbps, 60/30Mbps = 2. If you have a 60Mbps you're 4K Netflix will be back down to 1 second.
Modern games often gave 60-80GB update files (note capital B for Bytes, internet is in lower case b for bits, 8 bits in a Byte so we multiply this by 8). 80GB = 655360Mb.
Divide that by 30Mbps = 364 minutes to download. 60Mbps = 182 minutes. Plus any other data you're using, if you're watching Netflix while it downloads, you'll increase that time a bit.
For the most part, MOST people can be pretty happy with a 25Mbps download and not really notice the difference no matter how high the speed goes. Notable exceptions is gamers who frequently need game updates and professions that work in media. If you have multiple 4K televisions, that number moves up to about 50Mbps to be really happy with the speed.
Same rules apply here, except that many internet service has really low uploads. Many 25Mbps internet plans come with a 5Mbps upload. This is generally fine, but as the world changes and the way we all use internet services change that is starting to become a problem. Notable struggles with low upload speeds are poor Zoom call performance, slow backups, and since it takes longer to upload, more congestion on your service which means latency often suffers because of buffer bloat.
Services like Spectrum or Comcast often have plans like 300Mbps with 10-20Mbps uploads. This is a generally acceptible upload except for the uses noted above. Newer fiber services are often syncronouse, or have download and upload at the same speeds such as 500 download and 500 upload. These offerings are not exclusive to fiber vendors though, and these speeds are also just guard rails in case you need them. They may not actually fit your use case well and you could be overpaying or assuming a specific product is better automatically.