Megabyte (MB)
Definition: A megabyte (MB) is a multiple of the unit byte for digital information. The prefix mega means 10^6 in the International System of Units (SI). Therefore, one megabyte is one million bytes. The unit symbol for the megabyte is MB.
Binary vs. Decimal: In the binary system (base-2), used by most operating systems, one megabyte is equal to 1,024 kilobytes (2^20 bytes = 1,048,576 bytes). However, storage manufacturers often use the decimal system (base-10), where 1 MB = 1,000 KB. This is why a "500 MB" file shows slightly less in your computer.
Usage: Megabytes are commonly used to measure the size of files, such as high-resolution images, short audio clips, and documents. They are also used to measure the amount of memory in older computer systems.
Kilobyte (KB)
Definition: A kilobyte (KB) is a multiple of the unit byte for digital information. The prefix kilo means 10^3 in the SI. Therefore, one kilobyte is one thousand bytes. The unit symbol for the kilobyte is KB.
Binary vs. Decimal: In the binary system, one kilobyte is equal to 1,024 bytes. In the decimal system, it is exactly 1,000 bytes.
Usage: Kilobytes are typically used to measure the size of very small files, such as text documents, small images, and snippets of code.