Compression

File compression is a method of reducing the amount of storage space a file requires by encoding its data more efficiently. Rather than storing every value individually, compression algorithms identify patterns and redundancies that can be represented in a more compact form. A straightforward example is run-length encoding, where a long sequence of repeated values is replaced by a single count paired with the value itself, dramatically cutting the volume of data that needs to be stored or transmitted. Graphic files illustrate how significant these savings can be. An uncompressed bitmap stores color information for every pixel independently, which at 24 bits per pixel quickly adds up across even a small image. If that image uses only a handful of distinct colors, each pixel can instead be represented by a short index code pointing to a defined color table, reducing per-pixel storage from 24 bits to as few as 2 bits and cutting overall file size substantially. This principle underlies many of the compression schemes used in modern image formats. On Windows, compression can be applied in two practical ways. A file's Advanced properties include a compression attribute that, when enabled, instructs the operating system to store the file in a compressed state transparently. Alternatively, files can be placed into a compressed ZIP archive, a portable format that bundles and compresses one or more files into a single smaller package suitable for storage or transfer. Both methods achieve the same fundamental goal of reducing the disk space a file or collection of files consumes.