A '''low-density parity-check code (LDPC code)''' is an [[error correcting code]], a method of transmitting message over a [[signal noise|noisy]] transmission channel. While LDPC and other error correcting codes cannot guarantee perfect transmission, the probability of lost information can be made as small as desired. LDPC was the first code to allow data transmission rates close to the theoretical maximum, the [[Shannon Limit]].
Impractical to implement when developed, LDPC was forgotten. The next 30 or so years
of [[information theory]] failed to produce anything one-third as effective and LDPC remains, in theory, the most effective developed to date (2005). The explosive growth in information technology has produced a corresponding increase of commercial interest the development of highly efficient data transmission codes as such codes impact everything from signal quality to battery life. Although implementation of LDPC codes has lagged that of other codes, notably the [[turbo code]], the absence of encumbering [[software patents]] has made LDPC attractive to some and LDPC codes are positioned to become a standard in the developing market for highly efficient data transmission methods.
