 When we're measuring information, the basic unit we use is a bit, but there's another unit that we come across which is bytes What's the relationship? Well, it's safe to assume in most cases that one byte contains eight bits Now in the past it wasn't always the case and that a byte was not or necessarily eight bits But nowadays and at least for the courses that I cover you can assume that one byte is eight bits in length So now we have two different units bits and bytes The symbols used it's common to use a lowercase b for a bit and an uppercase b for a byte So when you see the units and combine with different prefixes try to distinguish between bits and bytes Of course it becomes a little bit more complex because the prefixes when used with bits and bytes Unfortunately differ and it depends upon the context or the the domain where they're used for example with communications data networking Often the prefixes of kilo mega giga Terra Using what we commonly know as the the decimal prefixes of 10 to the power of 3 10 to the power of 6 and so on But when we talk about storage those same prefixes K, M, G and T Commonly refer to slightly different values and in their binary Forms 2 to the power of 10 for kilo to the power of 20 for mega to the power of 30 to the power of 40 and so on Note that different values That is if we have One kilobyte What does K mean? well If K is 10 to the power of 3 then that is 1 by 10 to the power of 3 bytes Which is 1000 bytes Which is the common meaning of K when we talk about communication systems But we're talking for example about a hard disk size file size and storage 1 kilobyte What does the K mean? Well that commonly means 2 to the power of 10 So we get 1 times 2 to the power of 10 bytes and 2 to the power of 10 is 1024 of course different values similar or close but different So what does K mean? Well, it unfortunately depends upon the the context where we're talking about communication systems or storage systems If we're just dealing with approximate values, then it doesn't really matter because as we see that 1,000 and 1,024 are about the same But if we want to be precise then we need to know Whether K is 10 to the power of 3 or 2 to the power of 10 In the courses that I teach we will deal with mainly communications and we'll assume that all the values that I present The decimal 10 to the power of 3 10 to the power of 6 and so on just to keep things simple as another example if we have 2kb using our standard notation that is 2 to the power of 2 times 10 to the power of 3 bytes Which is 2,000 bytes which is 2,000 2,000 multiplied by 8 bits Because we have 8 bits in one byte so 16,000 bits 2 kilobytes is equal to 16,000 bits But of course if we use the other notation for the prefix K where K was 2 to the power of 10 It would be slightly different and you can check the answer. It would be equal to 16,384 bits So again, if we're approximating the prefix of The decimal 10 to the power of 3 or the binary 2 to the power of 10 makes very little difference But if you want to be precise make sure you know what prefix is being used and For the courses I teach will assume the decimal prefixes of 10 to the power of 3 10 to the power of 6 and so on so You should know about the common units which are in use The prefix is available and especially the the assumption that One byte equals 8 bits and the prefixes that we're going to use are 10 to the power of 3 10 to the power of 6 for Mega 10 to the power of 9 for giga and so on