Along with shutter speed and aperture, ISO is one of the three fundamental exposure parameters, and as such, mastering it is crucial to taking full control of your images. If you are new to photography, check out this fantastic video tutorial that will show you the ins and outs of how ISO works and how to use it.
Coming to you from David Bergman with Adorama TV, this excellent video tutorial will show you everything you need to know about ISO. By far, the most common mistake I see beginners make with ISO is leaving it too low in an attempt to preserve image quality, resulting in shutter speeds that are too slow to prevent blur due to subject motion or camera shake. The important thing to remember is that you can always work on the noise in a photo in post (in fact, modern noise reduction software is impressively advanced), but once a shot is blurry due to one of the aforementioned factors, you generally can't do much to save it. Check out the video above for the full rundown from Bergman.
If you would like to continue your photography learning journey, be sure to check out our range of tutorials in the Fstoppers store.