Compression is the process of reducing data size by discarding some information, which decreases quality and is an irreversible action.
The process that involves reducing the number of bits needed to represent something, where some information is lost and the process is not reversible, is known as compression. This loss of data is what makes compression an irreversible process. When compressing a photo using JPEG compression, for example, similar colors in the pixels are analyzed, and unnecessary colors are discarded, leading to a reduction in file size. This process results in a loss of photo quality, especially when excessive compression is applied.
So, compression is key for reducing data size but comes at the cost of decreasing quality and is irreversible once applied.