Initially identified as a key phosphoinositide that controls membrane trafficking at the Golgi complex, phosphatidylinositol‐4‐phosphate (PI4P) has emerged as a key molecule in the regulation of a diverse array of cellular functions. In this review we will discuss selected examples of the findings that in the last few years have significantly increased our awareness of the regulation and roles of PI4P in the Golgi complex and beyond. We will also highlight the role of PI4P in infection and cancer. We believe that, with the increasing number of regulators and effectors of PI4P identified, the time is ripe for a more integrated approach of study. A first step in this direction is the delineation of PI4P‐centered molecular networks that we provide using data from low and high throughput studies in yeast and mammals. Intra‐ and extracellular stimuli generate localized pools of PI4P through the dynamic localization of PI4 kinases and PI4P phosphatases. PI4P recruits effector proteins, often in cooperation with accessory factors, to distinct membrane districts thus mediating multiple compartment‐specific cellular functions.