What is a megabyte, gigabyte, bit, and byte?

byte – a unit of measure for digital information equal to 8 bits.

i.e. “You have 200 gigabytes of free space on your hard drive.”
“Your photo is too large. Please upload a file under 4MB (megabytes).”

One of my computer science professors in college explained it this way:

Your computer stores information in cubby holes – lots of cubby holes. One cubby hole can hold one bit of information. One byte equals 8 bits of information. Computers only understand numbers, so each bit, or each cubby hole,

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