MicroRNAs (miRNAs) are small 22-nucleotides long non-coding RNAs that regulate the gene expression through translational repression and mRNA degradation in varieties of species. miRNAs play regulatory role in several fundamental biological processes from normal development to regulation of stem cells, cancer stem cells and various human diseases including cancer. miRNAs can be used as potential biomarkers for disease diagnosis and have been considered potential therapeutic strategies in cancer treatment. This is a timely and specialized book providing the current understanding of miRNAs and their potential application in cancer diagnosis, prognosis, and therapeutic strategies in cancer treatment. This book will be a valuable source of information for the scientists in the field of cancer research as well as undergraduate and graduate students who want to pursue their research careers in cancer biology.