What is the main feature of the APFS file system?

The main feature of the APFS (Apple File System) is its optimization for solid-state storage. This file system was specifically designed to take full advantage of the capabilities of SSDs, enabling faster access times and improved data integrity. APFS includes features such as copy-on-write, which allows for efficient operation of snapshots and cloning of files and directories without needing to make full copies of the underlying data.

By optimizing performance on solid-state drives, APFS enhances speed and responsiveness when accessing files or performing operations like duplicating or moving data. Additionally, its features are tailored to the needs and characteristics of SSD technology, allowing for better overall efficiency in data storage and management on devices that utilize these drives.

The other options do not focus on this crucial aspect of the APFS.