In this paper, we present the evolution of software-defined radio (SDR) technology and show how it is currently at the forefront of numerous advances within the wireless sector, enabling new applications considered unrealizable only a decade ago. Specifically, this paper focuses on SDR from a discrete-time sampling perspective and discusses the efforts that are currently being pursued in order to further bridge the gap between these discrete-time samples, the hardware used to generate this information from continuous-time over-the-air signaling waveforms, and the software and digital logic used to process these samples into digital data via baseband processing. Given the extensive deployment of SDR technology across a growing number of applications, such as national defense, public safety, connected vehicles, education, and scientific research and development activities, it is vitally important that the wireless community understands the features, advantages, and limitations of this technology. With its versatility, cost, and functionality continuously improving, SDR has become a viable solution for prototyping wireless transceivers and networks that are much more tailored to specific applications and performance requirements relative to available off-the-shelf wireless solutions. To highlight the advantages and current issues with SDR technology, this paper presents several examples using a recently released, commercially available SDR platform.