Understanding compression algorithms helps you choose the right method for your needs. From the foundational LZ77 and Huffman coding to modern algorithms like Brotli, each compression method has unique characteristics. This comprehensive overview explores major compression algorithms, how they work, and when to use each.

Lossless vs Lossy Compression

Compression algorithms fall into two categories:

Lossless Compression:

• Original data can be perfectly reconstructed
• Used for text, code, databases, archives
• Examples: Gzip, ZIP, PNG

Lossy Compression:

• Some data is permanently lost
• Used for images, audio, video
• Examples: JPEG, MP3, MP4

This article focuses on lossless compression algorithms used for text and data files. According to Wikipedia's lossless compression article, lossless algorithms are essential for data where perfect reconstruction is required.

LZ77 Algorithm

LZ77 is a dictionary-based compression algorithm developed by Abraham Lempel and Jacob Ziv in 1977. According to Wikipedia's LZ77 article, it works by:

Finding repeated sequences in data
Replacing them with references to earlier occurrences
Using a sliding window to limit memory usage
Creating a dictionary of previously seen patterns

LZ77 is the foundation of many modern compression algorithms, including DEFLATE. The algorithm is particularly effective on text files with repetitive content.

Huffman Coding

Huffman coding is an entropy encoding algorithm that assigns shorter codes to more frequent symbols. According to Wikipedia's Huffman coding article:

Builds a binary tree based on symbol frequencies
Assigns variable-length codes to symbols
More frequent symbols get shorter codes
Minimizes average code length

Huffman coding is optimal for fixed symbol sets and is used in combination with LZ77 in DEFLATE.

DEFLATE Algorithm

DEFLATE combines LZ77 compression with Huffman coding. According to the DEFLATE specification (RFC 1951):

LZ77 stage finds and replaces repeated sequences
Huffman stage encodes the result with variable-length codes
Two-stage approach achieves better compression than either alone

DEFLATE is used in:

Gzip compression (as specified in RFC 1952)
ZIP file format
PNG image format
HTTP content encoding

According to Wikipedia's DEFLATE article, it's one of the most widely used compression algorithms, achieving 60-90% compression on text files.

Brotli Algorithm

Brotli is a modern compression algorithm developed by Google. According to Wikipedia's Brotli article:

Uses context modeling for better compression
Achieves 15-20% better compression than DEFLATE
More CPU-intensive than DEFLATE
Specified in RFC 7932

Brotli is becoming the preferred compression method for web content, especially static assets. According to web.dev's compression guide, Brotli provides better compression ratios for modern web applications.

LZMA Algorithm

LZMA (Lempel-Ziv-Markov chain Algorithm) is used in 7-Zip and XZ compression. According to Wikipedia's LZMA article:

Provides better compression than DEFLATE
Much slower compression and decompression
Used for archiving and distribution
Not suitable for real-time web compression

Zstandard (Zstd)

Zstandard is a modern compression algorithm developed by Facebook:

Faster than DEFLATE with similar compression ratios
Better compression than DEFLATE at higher levels
Used in databases and file systems
Gaining adoption in web applications

Run-Length Encoding (RLE)

RLE is a simple compression algorithm:

Replaces repeated characters with count and character
Very fast but limited effectiveness
Used in simple image formats like BMP
Not suitable for general-purpose compression

Choosing the Right Algorithm

Algorithm selection depends on requirements:

Web content: Gzip (compatibility) or Brotli (better compression)
Archives: ZIP (DEFLATE) or 7-Zip (LZMA)
Real-time: Gzip or Zstandard (fast compression)
Maximum compression: Brotli or LZMA (slower but better)
Universal support: Gzip (works everywhere)

Performance Comparison

Typical performance characteristics:

Gzip: Fast compression, good ratios, universal support
Brotli: Slower compression, better ratios, modern browsers
LZMA: Very slow compression, best ratios, archiving
Zstandard: Fast compression, good ratios, modern alternative

According to web.dev's compression guide, Gzip and Brotli are the most practical choices for web applications.

Algorithm Evolution

Compression algorithms continue to evolve:

1977: LZ77 algorithm developed
1952: Huffman coding invented
1990s: DEFLATE combines LZ77 and Huffman
2015: Brotli released with better compression
2016: Zstandard released with speed improvements

Conclusion

Understanding compression algorithms helps you choose the right method for your needs. DEFLATE (used in Gzip) remains the most widely supported, while Brotli offers better compression for modern applications. Each algorithm has trade-offs between compression ratio, speed, and compatibility. Choose based on your specific requirements: compatibility (Gzip), compression ratio (Brotli), or speed (Zstandard).

Compression Algorithms Overview: Understanding Different Compression Methods