60 years since "kpb wcy xz" became more informative than "I love you"

We have attempted to give a gentle overview of the concept of information theory, proposed by Claude E Shannon in 1948. Though the idea of "informative message" as per Shannon's theory is counterintuitive, on closer inspection, it is found to be not so. We have demonstrated the application of information content and information entropy on a couple of types of symbol sequences. Primarily, such analysis provides us with limits of compression possible on the sequences. However, wider scope has also evolved in analyzing sequences, especially biosequences like DNA, RNA and amino acids, to derive informational signatures in the sequences to classify them or to detect hidden features.