Web Open Font Format. File are OTF or TTF with compression and metadata supported by most of the popular browsers. An advantage is that the font data is compressed, so website that uses WOFF file will load faster.
WOFF (Web Open Font Format) is a font file format used to store fonts for use on the web. It was introduced in 2009 as an extension of the TTF (TrueType Font) and OTF (OpenType Font) formats, and has since become a popular choice due to its ability to deliver high-quality fonts with efficient compression. The WOFF file format stores font information as a collection of tables that describe the shape and appearance of each character in the font. Each table contains information about the x-height, ascenders, descenders, and other characteristics of the character, as well as advanced features such as ligatures and contextual alternates. The size of a WOFF file depends on the number of characters and the complexity of the font, but it is generally smaller than TTF or OTF files due to its efficient compression algorithm. One of the main advantages of WOFF files is their ability to deliver high-quality fonts with efficient compression. This makes them ideal for use on the web, where font sizes can vary greatly depending on the user's screen size and resolution.