APFS is a new file system developed by Apple to replace HFS+ and support SSD storage. It offers faster speeds, instant file duplication, increased file limits, and better crash protection compared to HFS+. However, it is not compatible with older macOS versions and does not support Windows/BootCamp read/write access. Data can be lost from APFS due to various causes like upgrades, corruption, or emptying the trash. Stellar Phoenix Mac Data Recovery software can recover lost files from APFS volumes on High Sierra by scanning, previewing, and saving files.