Why is compression used?

• A. It makes files take up less disk space and are quicker to download
• B. It duplicates files to the same location
• C. It slows down downloads
• D. It encrypts data

Answer: (A)

Compression reduces the amount of data by encoding information more efficiently, removing redundancy so the same content takes fewer bits. That means you can store the data in less space on disk and move fewer bits over the network, which translates into smaller files and faster downloads. When you retrieve the data, you can decompress it back to its original form (in the common lossless case), or, in some scenarios, to a close approximation if lossy methods are used. The trade-off is that compression and decompression require CPU time, and some data doesn’t shrink much at all, or may lose some quality if a lossy method is used. Nonetheless, the primary benefit centers on saving storage and speeding up transfers, which is why compression is widely used. Duplicating files doesn’t reduce size, encryption changes security and can add overhead, and slowing down downloads is not the purpose of compression.