For example, trillion means one million yuan, which is generally represented by M, and thousand is generally represented by K. Mega bit (Mb) refers to one million bits, and thousand bit (Kb) refers to one thousand bits. By analogy, MB is one million bytes and KB is one thousand bytes. GB refers to one thousand megabytes, or 1000MB. Note that the "thousand" here is not 1000, but 1024. The rest can be deduced by analogy.
Network communication, data storage hardware, etc.
