A megabyte is 106 or 1,000,000 bytes.
One megabyte (abbreviated "MB") is equal to 1,000 kilobytes and precedes the gigabyte unit of measurement. While a megabyte is technically 1,000,000 bytes, megabytes are often used synonymously with mebibytes, which contain 1,048,576 bytes (220 or 1,024 x 1,024 bytes).
Megabytes are often used to measure the size of large files. For example, a high resolution JPEG image file might range in size from one to five megabytes. Uncompressed RAW images from a digital camera may require 10 to 50 MB of disk space. A three-minute song saved in a compressed format may be roughly three megabytes in size, and the uncompressed version may take up 30 MB of space. While CD capacity is measured in megabytes (typically 700 to 800 MB), the capacity of most other forms of media, such as flash drives and hard drives, is typically measured in gigabytes or terabytes.
NOTE: For a list of other units of measurement, view this Help Center article.