The research within information theory is focused on understanding the underlying factors that determine the error correcting capabilities of convolutional codes. In addition to structural properties of convolutional encoders, development and analyses of efficient decoding algorithms for (block and) convolutional codes are covered. Presently, efforts are concentrated on construction of and decoding methods for codes on graphs. Using graph-based methods a rate R=5/20 convolutional code with overall constraint length 67 was constructed. Its free distance was determined to be as large as 120.