Focal plane shutters are by far the most common mechanism for controlling exposure times, but leaf shutters are still around and preferred by some photographers, particularly when it comes to working with flash. This excellent video will show you the advantages of a leaf shutter when working with a strobe.
Coming to you from David Bergman with Adorama TV, this helpful video will show you the advantages a leaf shutter has over the more common focal plane shutter when working with flash. For the most part, leaf shutters exist in the medium format realm, though there are a few to be found outside it, perhaps most notably in the Fuji X100 series of cameras. You might be wondering why photographers do not just use technologies like high-speed sync. Many do, but there are disadvantages to HSS, the most notable being a loss of maximum power, which can be a problem when you are competing with the midday sun. Personally, HSS has made my life a lot easier, but some photographers still have a strong preference for leaf shutters, even going so far as to invest in medium format systems to retain the capability. Check out the video above for the full rundown from Bergman.