Please forgive the stupidity of this question, but inquiring minds (okay... just me) want to know. Throughout my short-lived riding career, I rode in primarily western tack. A few months before I quit riding, I found myself on a horse that wore English tack and fell in love with the style. This horse wore a plain raised snaffle bridle and I didn't have much of an opportunity to learn more because I quit riding shortly thereafter.
Now, I'm researching English tack for my new horse and I've come across these curious bridles advertised as 'flash' and 'crank'. What are their purposes? How are they supposed to be used? On what type of horse would you use something like this? I've tried Google and there are a lot of pictures of each bridle, but nothing that really answers my questions. So far, I've found that these bridles are used to keep a horse's mouth shut - is that the only reason?
For the record, I plan to start my mare in a simple snaffle bridle with some sort of mild bit - I'm thinking a French link d-ring to prevent any pinching. She's a retired harness racer, but has been off long enough (11 years) for me to hope that her mouth has softened up considerably and she won't require a harsher bit.