gzip without tar? Why are they used together?

TAR creates a single archived file out of many files, but does not compress them. Format Details A tar file is the concatenation of one or more files. Each file is preceded by a 512-byte header record. The file data is written unaltered except that its length is rounded up to a multiple of 512 bytes and the extra space is zero filled. The end of an archive is marked by at least two consecutive zero-filled records. GZIP compresses a single file into another single file, but does not create archi…