The prefix "mega-" is derived from the Greek word "megas," meaning large or great. It is commonly used in various fields, such as science and technology, to denote a factor of one million (10^6). For example, in computing, a megabyte (MB) represents approximately one million bytes of data. In everyday language, "mega-" can also describe something that is exceptionally large or impressive. For instance, a mega sale refers to a significant discount event, while a mega city describes a highly populated urban area. This prefix helps convey the idea of scale and magnitude in different contexts.