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ext4

The default filesystem on most Linux distributions.

ext4 is the fourth-generation Extended filesystem, the successor to ext3 that became the default on most major Linux distributions in the early 2010s. It supports very large volumes (up to 1 EiB) and individual files (up to 16 TiB), delayed allocation, journal checksums, extents-based block allocation (rather than the older block-list approach), and nanosecond-precision timestamps.

Theodore Ts'o is the long-standing lead maintainer. ext4 is the "safe choice" filesystem on Linux: stable, well understood, with excellent tool support (e2fsprogs covers fsck, mkfs, tune2fs, resize2fs, debugfs, dumpe2fs). It is a sensible default when you don't have a specific reason to use Btrfs (snapshots), ZFS (data integrity), or XFS (large-file throughput).

ext4 ships preinstalled on every Linux distribution. The format is mature and remarkably stable; new in-kernel improvements (case-folding for case-insensitive directories, large-folio support, fast commits) have continued to land in recent kernel releases without breaking compatibility with older tools.

Built into the Linux kernel; userspace tools:
  Debian/Ubuntu: sudo apt install e2fsprogs
  Fedora/RHEL:   sudo dnf install e2fsprogs
  Arch:          sudo pacman -S e2fsprogs