The ".rar" file format is a type of compressed archive file used to store one or more files in a smaller size. It was developed by Eugene Roshal and is commonly used for file compression and data packaging. RAR files can contain various types of data, including documents, images, and software, making them useful for sharing large files over the internet. To open and extract files from a .rar archive, users typically need specific software, such as WinRAR or 7-Zip. These programs allow users to decompress the files, restoring them to their original size and format. The .rar format is known for its efficient compression algorithms, which can reduce file sizes more effectively than some other formats.