"ACM's first classification system for the computing field was published in 1964. Then, in 1982, the ACM published an entirely new system. New versions based on the 1982 system followed, in 1983, 1987, 1991, and 1998. The 2012 scheme utilizes a new poly-hierarchical structure and a more in-depth approach than the 1998 version. It no longer uses the letter-and-number coding of the previous versions. The old scheme has been mapped to the new, and both the 1998 and 2012 terms are available on Citation Pages of all indexed articles in the ACM Digital Library. The 2012 ACM Computing Classification System has been developed as a poly-hierarchical ontology that can be utilized in semantic web applications. It replaces the traditional 1998 version of the ACM Computing Classification System (CCS), which has served as the de facto standard classification system for the computing field. It is being integrated into the search capabilities and visual topic displays of the ACM Digital Library. It relies on a semantic vocabulary as the single source of categories and concepts that reflect the state of the art of the computing discipline and is receptive to structural change as it evolves in the future. ACM will a provide tools to facilitate the application of 2012 CCS categories to forthcoming papers and a process to ensure that the CCS stays current and relevant. The new classification system will play a key role in the development of a people search interface in the ACM Digital Library to supplement its current traditional bibliographic search."