After IoT devices have been deployed into the world, it may be necessary to update them for additional security or functionality but gaining physical access to the device may no longer be possible or might be very costly. In 2015, Fiat Chrysler Automobiles, the world's seventh largest automaker, issued a safety recall notice for 1.4 million vehicles in order fix a software hole that allowed hackers to wirelessly break into some vehicles and electronically control vital functions. Vehicle owners were left on their own to install the patch, which would typically be done by downloading the patch to a USB drive, then plugged into a vehicle port and uploading (source).
Fortunately today, there are over-the-air (OTA) software and firmware updates that allow embedded devices to be reprogrammed over their wireless connection instead of with a physical hardware device. In short, an OTA update is the wireless deployment of new software, firmware or other data to edge devices /Internet of Things use cases like consumer electronics, automobiles and smart sensors.