Double action is when the first trigger pull will cock the hammer, and pulling it all the way will release the hammer and fire the round. Some revolvers are the same way.
A single-action means you have to cock the hammer to get ready to fire. The 1911 is like this. Most people carry a 1911 "cocked and locked" which is with the hammer in the cocked position and the safety on to keep it from firing. After the first round is fired, a 1911 will re-cock itself and be ready to fire again. Of course, a Beretta 92 will also, so really this difference only applies to how the first round is discharged.
-Both have their strengths and weaknesses, and both have been through ups and downs of popularity. There was a time when a 1911 was cheap and not well-regarded. 1911s are worth a fortune these days. also, 9mm is a bit less in favor than it used to be-due to the current popularity of the .40. Back in 1990, you would have been a fool not to have run right out and gotten a 10mm. Pay no attention to this herd mentality. I have seen many of these cycles and you will too-if you follow guns for a few decades or so.
I laugh at the fact that a lot of people call the 9mm a "mouse round" nowadays. It is funny to me that people think only a .40 or .45 can kill you. Just look at a little history, an you will see that the nazis killed hell out of literally million with 9mm. The round works. So does a .38 for that matter. I can remember all the way back to the day that most cops carried .38 every day-in a (blasphemy) revolver!
My theory is to find a pistol you like, learn to shoot well, and shoot a lot. Personally, my favorite pistol of right now is my 9mm Glock 19. I like having no switches or hammers to fool with. Nothing to remember, just pull the trigger-and keep pulling until it is empty. Many may scold me for my "idiot gun" or "mouse pistol" or "plastic trash." Whatever. I like it. It feels good, and I have been an avid shooter for the last 35 years, so I have enough experience to know what I like, and yes, I do know what all those knobs and switches on all the sigs and S&Ws and so forth are for.
One of the great things about firearms for me is that there is something for everyone. The 1911 is fun to shoot, but I don't carry it. The Glock may feel cheap and strange to some people-that's O.K. The $800 sig may be perfect for some people, the $1000 HK may float some other guy's boat. What I like now may change in a year or two as well. There are so many ways to skin a cat. You should hang out at the range, maybe even rent a few different semis, and you will find one you enjoy. That is what you should settle on, even if it is a currently out-of-favor "mousegun" or revolver.
*There is a strong motivation amongst gun owners to have the "latest and greatest " to show all their pals. This is what I believe drives these popularity cycles. Personally, I don't care at all about impressing someone with my shiny new gun. I would rather take my beat up old model 12 shotgun to a dove field and impress then with a pile of dead birds rather than 5 boxes of empty shells.
One of the best post I have read. Good job man!