Wireless technology is one of the enabler for Internet of Things (IoT) with a tremendous expected growth in the next years. The variety of wireless technologies to support different requirements like coverage or network architecture transform the wireless industry in a very competitive segment. There are many solutions for short and middle range IoT communication however, there is not still a long range solution that is broader adopted by the industry, which is generally know as Low-Power Wide-Area (LPWAN) technology. There LPWAN has not been designed for mobile network but the 3rd Generation Partnership Project (3GPP), that is responsible for 3G and 4G standardization, created the new technology that is named Narrow-Band IoT (NB-IoT) which intends to be widely adopted by the Operators. This article presents a summary of the NB-IoT specifications and some comparisons with others LPWAN technologies.