If you're wondering WHY every place makes you pick a password with at least one capital letter, one number, and one symbol, it's because of one guy.
Bill Burr worked for the National Institute of Standards and Technology in 2003, and he was put in charge of coming up with the rules for good passwords...even though he wasn't a security expert and didn't even know that much about the subject.
And now, he says he's SORRY. There's two reasons: One, because those passwords are super annoying...and two, because more research has proven they're not even that effective.
It turns out that passwords that are LONGER are much more secure.
If your password is four random common words...like, say, "purple-trombone-dancing-bucket"...that would take hackers HUNDREDS of years longer to hack than our current shorter, randomized passwords.