What is data compression, and why is it useful?

• A. Reducing data size for storage or transmission; saves bandwidth and space.
• B. Increasing data redundancy to improve reliability.
• C. Encrypting data for security.
• D. Converting data from one format to another without reducing size.

Answer: (A)

Data compression means representing information with fewer bits than the original by encoding patterns and removing redundancy. This is useful because it reduces the amount of data that needs to be stored or transmitted, saving storage space and bandwidth, which speeds up transfers and lowers costs. There are two main forms: lossless compression, which lets you perfectly reconstruct the original data, and lossy compression, which removes some detail to achieve higher reduction and is common for media like images and audio. The other options miss the point: increasing redundancy would make data larger, encryption is about security rather than size, and converting formats without reducing size doesn’t actually compress.