21st century is known as an age of learning. It was declared to be the age of information and communication technology due to the revolution of mobile technology. Mobile technology has become an integral part of our lives. We cannot work in the society without mobile, internet etc. every body is using online technology in day today working. According to Telecom Regulatory Authority of India (TRAI), “India had 456.7 million mobile subscribers…”. Mobiles are not just a playing but beyond it, it is an amazing educational tool for teaching and learning process. M-learning is the new sensation in the field of education. M-learning is now creating a new wave of educational development for sustainable and viable learning option. It is based on the convergence of mobile technologies and wireless infrastructure. The present paper highlights the concept of M-learning, Characteristics, Types, Significance, M-Learning System, Categories of Mobile learning and their Technologies, Advantages and Disadvantages of M-learning.