A BZ file is generally a bzip2-compressed file, meaning it’s not a document format but a compressed package, usually seen as `.bz2` (with older `.bz` also existing), and it normally expands back into one original file—like `data.csv.bz2` turning into `data.csv`—while variants such as `.tar. If you are you looking for more info about BZ file application check out our own web-page. bz2`/`.tbz2` pack multiple items inside a tar archive before compression; bzip2 works well on text-heavy data by making redundancy more compressible, though it’s slower than some methods, and tools like 7-Zip, WinRAR, The Unarchiver, Keka, or Linux’s `bunzip2`/`tar -xjf` handle extraction, with the filename hinting whether you’ll get one file or many.

To open a BZ/BZ2 file it’s essential to tell whether it’s plain bzip2 or tar.bz2, as `.bz2/.bz` restores one file but `.tar.bz2/.tbz2` gives a `.tar` first that you then unpack; extraction tools like 7-Zip/WinRAR on Windows, The Unarchiver/Keka on macOS, and `bunzip2`/`tar -xjf` on Linux all handle this, and opening it in an archiver lets you see immediately whether it contains a tarball or just one file.

Under the hood, bzip2 makes files smaller by converting scattered repetition into compressible runs, allowing compact run-length and symbol encoding while keeping precise reversal instructions so the output restores perfectly; it often produces smaller results than gzip or common ZIP settings on logs and code but at higher CPU cost, fitting archival workflows, and it became a common Unix/Linux packaging choice for source distributions thanks to predictable behavior and solid compression without the extreme slowness of high-end xz modes.

ZIP and gzip target different use cases, with gzip known for speed and streaming in `.gz`/`.tar.gz` formats, and ZIP acting as a multi-file bundle common on Windows but offering variable compression; bzip2 combined with tar (`.tar.bz2`) delivers stronger, consistent compression and fits a Unix-centric niche where size efficiency is preferred over raw speed.

bzip2 exists because it prioritizes compression strength over raw speed, often yielding smaller files than gzip for repetitive text data but requiring more CPU, making it poor for speed-sensitive situations yet appealing for storage and distribution; ZIP acts as both container and compressor, while bzip2 is only a compressor, so Unix/Linux systems pair it with tar (`.tar.bz2`), and it remains common for source bundles, logs, and backups where reduced size is worth the slower performance.

You’ll sometimes see `.bz` and other times `.bz2` because both serve as labels for bzip2-compressed data, though `.bz2` eventually became the clearer, standardized choice; early Unix/Linux setups and legacy scripts often used the shorter `.bz`, but as tooling matured `.bz2` became the preferred, less ambiguous extension, and functionally both behave the same since extraction tools read the file header rather than the name, so old builds may still produce `.bz` while modern workflows favor `.bz2`, and either can be opened with 7-Zip/WinRAR, The Unarchiver/Keka, or `bunzip2` to restore the original file.