GZIP, short for 'GNU Zip,' is a file compression utility used in Unix and Linux systems. It reduces file sizes for efficient storage and faster transmission by utilizing the GZIP compression algorithm. Compressed files have a '.gz' extension and can be easily decompressed to their original state.

GZIP is commonly used for compressing individual files. It is also common practice to create compressed archives by gathering multiple files into a single TAR archive and then applying GZIP compression to that archive. The resulting file extensions would comprise both extensions, like the following: .tar.gz or .tgz.

In the code above, instantiate the IronGZipArchive class using the 'using' statement. Utilize the Add method to add the compressed TAR file to GZIP. Use the SaveAs method to export the GZIP file.