XDCC initially was a script for use on Internet relay chat (IRC) in the mid 1990s. It now is a file-serving IRC browser available as an add-on to an IRC client, and functions as a search engine. Sometimes XDCC is called Xabi DCC, after its initial developer. XDCC uses two types of commands: private message query (msg) to an IRC network bot and client-to-client protocol (CTCP) commands to a bot using an IRC client. XDCC servers typically handle only very large files, such as entire movies, in packets for downloading and uploading at extremely fast speeds. XDCC bots are often hacked computers at educational institutions or major corporations, chosen for their extreme transfer speeds above the speed of cable or digital subscriber lines (DSL).
There are XDCC uses that are legal, and one of these is a packaged XDCC in client software that enables the creation and publishing of dictionaries to compact discs (CDs) or digital versatile discs (DVDs). These can be monolingual, bilingual or multilingual, and they are capable of being customized with particular features and formatting to suit the market customer they are sold to, including adding customer logo and brand name to the dictionary. These come with features such as simple and advanced search features in a user-friendly interface; and to make the dictionaries searchable from other applications, there are application integration features.
This same client software can also be used in a process to produce dictionaries for websites. The dictionary content is indexed and furnished search and conversion capability uniformly, enabling multidictionary search within a website. For example, if a company has both a picture dictionary and a thesaurus, the search and indexing commands will uniformly pull from all of the dictionaries without the need for learning separate commands for each dictionary or delineating separate file paths. Semi-automation allows for updates and re-indexing of these dictionaries quickly with new terms.
During file-sharing, XDCC bots use a direct client-to-client (DCC) protocol to enable handshaking and use an IRC server for peers to interconnect and exchange files. The use of the IRC server is discontinued once the connection is made. Users can then request of the XDCC bot a list of its file packets available for download, and from that list, enter a command that will either start the download immediately or place the computer into a queue for downloading.
Most of XDCC usage is not only using unaware hacked computers as transfer stations, but also downloading illegal content. XDCC has a versatile interface and simple command structure, making it a tempting choice for some for these illegal purposes. There is this to consider, however: the Recording Industry Association of America (RIAA) and the Motion Picture Association of America (MPAA) are both actively and diligently scanning for hacked computer usage to prosecute to protect the profits of artists and their industries.