The International Standard Recording Code (ISRC) is an international standard code for uniquely identifying sound recordings and music video recordings. The code was developed by the recording industry in conjunction with the ISO technical committee 46, subcommittee 9 (TC 46/SC 9), which codified the standard as ISO 3901 in 1986, and updated it in 2001.
An ISRC identifies a particular recording, not the work (composition and lyrical content) itself. Therefore, different recordings, edits, and remixes of the same work should each have their own ISRC. Works are identified by ISWC. Recordings remastered without significant audio-quality changes should retain their existing ISRC, but the threshold is left to the discretion of the record company.
ISO 3901 was finished in 1986. In 1988, the IFPI recommended that its member companies adopt ISRCs for music videos. In 1989, the ISO designated the IFPI as the registration authority for ISRCs. The IFPI, in turn, delegated part of the administration of ISRCs to several dozen national agencies, which allocate ISRCs to both record companies and individuals. The national agencies began assigning ISRC codes for music videos in August 1989.
The Japanese recording industry began encoding ISRCs on audio CDs in November 1989. The IFPI and the Recording Industry Association of America (RIAA) then developed detailed recommendations for this practice, as well as for ISRC assignment in general. The IFPI adopted the recommendations in March 1991, and they went into effect for IFPI members on 1 January 1992.
ISRC codes are always 12 characters long, in the form "CC-XXX-YY-NNNNN". The hyphens are not part of the ISRC code itself, but codes are often presented that way in print to make them easier to read. The four parts are as follows:
The most common file formats that ISRC codes can be embedded into presently are MP3, M4A, AAC, FLAC, and WAV for audio. For video ISRCs, embedding is generally performed on MP4 or M4V files. It is worth pointing out that embedding ISRC into individual files for online distribution differs from embedding ISRC codes in CD. The Red Book standard recommends to also embed ISRCs onto CDs. The two types of ISRC embedding are not generally interchangeable and should be done separately. 
The standard for the ID3v2.2 tag, that was designed for use in MP3 files, and was published on March 1998, defined a way to embed ISRC in a 'TSRC' frame. On August 2012, the European Broadcasting Union published a specification for embedding ISRC in Broadcast Wave Format.
The provision of ISRCs is overseen by appointed national ISRC agencies. These national ISRC agencies issue codes directly to the public and may also utilize authorized ISRC Managers to issue ISRCs. In the United States, the appointed agency is RIAA. ISRC codes can be obtained in large blocks directly from RIAA for an administrative fee ($95 at time of this publication), in quantities as little as 1 from ISRC.com ($2-$5), or in conjunction with other music-related services from other authorized ISRC managers. In territories where there is no national ISRC agency, users can obtain ISRC codes directly from IFPI or from ISRC.com.