Turbo and LDPC (low-density parity check) codes are simple and new types of error correction codes which give a powerful and practical performance of error correction. Although experimental results show their efficacy, further theoretical analysis is necessary, which is not straightforward. We have built a unified framework of turbo and LDPC codes based on information geometry. The framework helps our intuitive understanding of the codes and opens a new prospect of further analysis. We have revealed some properties of these codes in the proposed framework. This paper summarizes the results.