Cells live in an ever-changing environment, always needing to be aware of their surroundings and reacting to an organism's needs. In order to understand when to take action, cells must receive a message from the outside world in a process called reception. Reception is the first of three steps in cell signaling. In this episode, we review how signaling molecules bind to receptors inside and outside of the cell, along with covering specific cell surface receptors like the G protein-coupled receptors, tyrosine kinases, and ion channel receptors.