The 1000 vs 1024 problem
Two unit systems share one set of casual names, and the confusion costs real capacity-planning errors. Decimal (SI) units multiply by 1000: a kilobyte is 1000 bytes, a terabyte is 1012. Binary (IEC) units multiply by 1024: a kibibyte (KiB) is 1024 bytes, a tebibyte (TiB) is 240. Drive manufacturers sell in decimal; most operating systems and tools report in binary, which is why a "1 TB" disk appears as roughly 931 GiB. Nothing is missing; the units differ by 2.4% per step, compounding to ~9% at the tera level.
Who uses which
Decimal: disk and SSD marketing, network transfer totals, S3 and most cloud billing, macOS Finder. Binary: Linux tools with -h (ls, du, free report KiB/MiB/GiB even when they print "K/M/G"), Windows Explorer (which prints "GB" but computes GiB, the worst of both worlds), RAM sizes always, and Kubernetes resource limits, where Mi and M are both legal and mean different things. A pod requesting 512M gets ~488 MiB; the suffix typo is a genuinely common cause of unexpected OOM kills.
Bits vs bytes
The bits row exists because network speeds are quoted in bits per second while files are measured in bytes, the factor of 8 that makes a "100 Mbps" line move at most 12.5 MB/s. For transfer-time math specifically, see the bandwidth calculator on this site, which handles the unit juggling for you.