Orthophoto or Raster Imagery
Acquired during the summer, the latest one  meter Orthophoto, or as it is mostly commonly called "raster imagery" or imagery for short, will serve as your visual backdrop by default for the U.S. The frequency of the intervals for the imagery is typically on a two  year cycle for many but not all states. Larger states, namely Texas, may come into a longer span of frequency for new imagery.
There is also a Photo Date layer. This layer will label the date and year on the mapping interface. Mostly, when you are working on or near interstate boundaries [when you have land from two states in view on the mapping interface] the imagery can appear different and you may want or need to be able to enable the Photo Date layer.
Historical datasets are made available for your use by choosing your desired year for that layer by choosing the desired, available year in a drop down.The earlier, older dataset's resolutions could be at a lower than one  meter. Regardless, it makes for an excellent resource if you are looking for anonomlies that may be occurring or have the potential to occur. You may also want to use it as another reference for any indication of possible activity if you are managing land from afar.
Canadian Air Photo Mapping Imagery
For the two Canadian provinces, Manitoba and Saskatchewan, that we serve, the imagery will auto switch to "Air Photo". However, the imagery here is for a span of years such as 2008 - 2010. Otherwise the behavior, as far as having the latest imagery or being able to disable the imagery layer is the same as the U.S. land imagery.