OSM is free and open - the data can be dumped and printed or used by anyone. In a disaster, they often print out large maps of an affected area for logistical planning. It also remains in the database, so people can use it in the future (and change it as reconstruction occurs). This 1 data set is used by many apps, so in general, making it better helps a lot of people, in a disaster, information is key. So let's say you are in a tent near the disaster and planning some aid. you all open google maps. Half the bridges are destroyed. Which ones? Does google update their map in 2 days? Nope, they need a lot more time. Sometimes google maps is the record of what *was* there, not what *is still* there. This is where OSM HOT and you come in. Normally, people mapping in OSM use standard images you see on mapping sites to help update the map(from bing, usually), but after a disaster all existing imagery is out of date - the actual post-disaster state is needed. Someone gets imagery - a plane, a new satellite image, a drone pic - any decent imagery after the disaster - and they use it to create a hot task - the link going to these tasks uses this special after-disaster imagery, so you can trace roads and make buildings that actually still exist - so planners can compare to existing maps and see what is damaged or undamaged and plan their resource use wisely. They can print out large planning maps to help with coordination. By you doing the difficult work of interpreting the imagery into a useful data set, you can help rescue efforts or aid programs operate better.