absolute URL Link specifying the complete path to a file. Contrast with relative URL.
codec Short for 'coder-decoder'; a device or computer program capable of encoding and/or decoding a digital data stream or analog signal.
compression A method for generating smaller files for transmission or storage, with the capability of regenerating the original data exactly (lossless compression) or approximately (lossy compression).
container A file format that specifies how different streams of data or files (such as encoded audio and video) can be stored or sent over a network together. Also called a wrapper. A particular container format can include video data in many encodings. The .ogg format combines Ogg Vorbis audio and Ogg Theora video, plus metadata. Matroska (.mkv), .mp4, and .avi containers can also contain Ogg Theora video.
decoder A device or computer program for converting a compressed or otherwise encoded file or data stream back to the original format and either the exact original data (lossless compression), or some approximation of it (lossy compression).
demultiplex Convert a file or stream containing multiple data streams to separate files or streams containing one stream each.
distribution In GNU/Linux and BSD, a set of software selected, maintained, and distributed under Free license by some organization or individual, including the operating system, essential utilities and data, and applications. For example, Ubuntu Linux or FreeBSD.
encoder A device or computer program for converting a source file or data stream to another format, usually compressed.
Firefogg Firefox add-on for encoding video in Ogg Theora while it is uploading to a Web site. Requires specific software in the Web server.
GUI Graphical User Interface
H.264 A patent-encumbered codec used by Apple, Youtube, and others.
HTML5 Version 5 of Hyper Text Markup Language, which includes new functions for managing video.
jar file Java archive file containing software written in Java.
key frame In video compression, a frame that is described in full, usually at the start of a scene or cut. Succeeding frames can be described by their differences from a preceding frame.
lossy In data compression and encoding, an irreversible algorithm that enables recovery of an approximate copy of the original data. Some lossy algorithms permit the user to set the degree of accuracy in the encoding step.
lossless In data compression and encoding, a reversible algorithm that enables recovery of a bit-perfect copy of the original data.
metadata Information about the contents of a file, such as title, author, and so on.
NGO Non-Governmental Organization, usually but not always a non-profit corporation.
patent, software A licensed monopoly on an idea or algorithm. The legality and desirability of software patents are hotly debated, and a good deal of ingenuity is put into circumventing them.
relative URL Link to a file starting from the current location in the file system. Contrast with absolute URL.
stream A continuous data transmission without a predefined size, as opposed to a file of some specific size.
streaming Real-time delivery of multimedia content, in contrast with downloading followed by playing.
torrent 1) Distributed download software such as BitTorrent, and its method of operation, in which pieces of a file are assembled from multiple sites. Users who have downloaded a file, and have more upload bandwidth than they need, offer to let others get part of the file from them. 2) Download software using a torrent client. 3) The tiny file that specifies how to torrent a much larger file.
transcode Change content from one encoding to another. When transcoding, best results are attained when starting from the originals, as successive lossy encodings lose quality with each step.
wrapper A container.