The use of the Internet of Things (IoT) and Cyber-Physical Systems (CPS) in industry and daily life has increased. The embedded software of IoT systems requires updates over time for long-term maintainability, bug xes, and improvements. Developers and manufacturers design and implement OTA update systems in ad-hoc manners because there are no speci c standards and little empirical information about mechanisms. This article describes a systematic literature review to identify proposed OTA update mechanisms, and a taxonomy to orga- nize them for system designers. Academic and professional (grey) litera- ture was gathered from four information sources; 109 studies were found, of which 29 remained after applying inclusion and exclusion criteria; and they were recognized as belonging to six mechanisms (categories). Each technique was associated to a mechanism, yielding an (initial) catalog of OTA update techniques. This taxonomy and catalog can be used to design IoT and CPS applications that must include OTA update functionality.