Wikipedia
VCDIFF
VCDIFF is a format and an algorithm for delta encoding, described in RFC 3284. The algorithm is based on Jon Bentley and Douglas McIlroy's paper "Data Compression Using Long Common Strings" written in 1999. VCDIFF is used as one of the delta encoding algorithm in "Delta encoding in HTTP" (RFC 3229) and is employed in Google's Shared Dictionary Compression Over HTTP technology used in their Chrome browser.