A quick overview that might be helpful to newer users about external data sources that OpenStreetMap has access to. Some users may not be aware that the major OSM editor applications dynamically change the available background imagery based on your current editing area. A lot of people may not know that JOSM lets you see the date that Bing imagery was captured which can either embolden remote edits for recent imagery or cause you to be more cautious for older imagery. Lastly, there is of course also Mapillary.