Reed-Solomon is an algorithm for Forward Error Correction (FEC).
Reed-Solomon was introduced by Irving S. Reed and Gustave Solomon of MIT Labs in Polynomial Codes Over Certain Finite Fields, which was published in the Journal of the Society for Industrial and Applied Mathematics in 1960.
Reed-Solomon does not specify a block size or a specific number of check symbols. These variables can be set to the best variables for each transmission medium.
DVB uses Reed Solomon coding configured to use blocks of 188 information symbols and 16 check symbols, which results in a total block size of 204 symbols.
Reed-Solomon is often abbreviated as RS.