First released in 1999, the .7z file extension was first released alongside the 7Zip open source archiving application. The format allows for any conversion, encryption or compression method to be applied. Because any of these methods can be used, the format is effectively future proofed. The file type also allows for its size to be extremely large and can achieve high rates of compression.
The 7z file extension allows for files of up to 16000000000 GB. 7 types of compression are currently supported. The default compression technique, LZMA, compresses at approximately 1MB/s and decompresses at up to 20MB/s. The file format supports the use of AES-256 encryption.
The .zip file extension is the most well known file type related to compressed and archived files. First released in 1989, the format is still widely used and is built into Microsoft Windows releases since 1998. It is also supported by Apple's OSX operating system. The ZIP format supports compression via several different techniques and even supports simply archiving of files without compression. Despite being 20 years old, the ZIP format looks set to continue to thrive whilst bandwidth and storage remain relatively costly.
The compression techniques used to create a .zip file do so by compressing each file individually. This has the advantage of potentially using different appropriate compression techniques for each file within the archive, however under normal circumstances it limits the potential compression capability. Although the ZIP format allows for up to 10 different types of compression to be chosen, the DEFLATE method is the most common. DEFLATE is based on Huffman coding.