1 bit is a single binary 1 or 0
2 bits = 1 nibble
2 nibbles = 4 bits = 1 word
2 words = 4 nibbles = 8 bits = 1 byte
1024 bytes = 1 Kilobyte (SI is KB not kb)
1024 KB = 1 Megabyte (SI is MB not mb or Mb)
1024 MB = 1 giga byte (SI is GB)
1024 GB = 1 terra byte (SI is TB)
off the top of my head I can't actually recall what comes next...