Habitat selection, resource selection, and space use are related concepts that lie at the foundation of much research and several applications in wildlife ecology, and it has long been emphasized in ecological theory. It is also highly relevant for spatial ecology because habitat selection is frequently viewed to operate at different spatial and temporal scales. Here, we first distinguish these concepts, briefly describe relevant theory for space use and habitat selection (including habitat selection theory and home range concepts), and finally provide an overview of common ways to quantify space use and resource selection with radio-telemetry data. We illustrate these concepts and models using radio-telemetry data on the endangered Florida panther (Puma concolor coryi). This example shows how different home-range estimators vary in the way they track space use over time and their ability to capture movement trajectories. Resource-selection functions illustrate non-random use of habitat by panthers across this region. We conclude by noting how resource-selection functions can be used to link habitat use and movement, providing an intuitive bridge between different topics in spatial ecology and conservation.