The ".7z" file format is a highly compressed archive, often using LZMA compression, developed in 1999 that supports AES-256 encryption and file splitting. It requires third-party software like 7-Zip, The Unarchiver, or PeaZip to open on Windows or macOS. For more information on opening 7z files, visit How-To Geek . Does 7z compress better than zip? - Microsoft Community Hub