I know absolutely nothing about these. I'm going to start my fall/winter wardrobe and plan to incorporate some sports jackets/blazers.

1. What's the difference between a sport jacket and a blazer?

2. More or less buttons for stylish, sharp casual wear?

3. When is it appropriate to button them or not?

4. What is single vs. double breasted?

5. Anything else I should know?

TIA all!

This is what I sport around town in:
http://www.kennethcole.com/scripts/shop/product.asp?pid=8059&cc=&title=&pw=thumbnail&var=0&srchtype=&srcharg=&size=0

Look for quality amongst anything else. It may cost you a bit more up front but the amount of use you'll get out of it will cover any monetary loss. 2 or 3 button won't make much difference regarding the overall look.

Sport jacket and blazer are in essence the same item. It's different only in the the accoutrements you wear with them and the place you'll be going. Classy/elegant vs casual/laid back.

Regarding buttoning, there is no set rule on buttoning your blazer. If you're wearing jeans and being casual it's an unwritten rule to not button it.

1. A sport jacket is an odd jacket, that is, the jacket from a suit worn without the trousers. A blazer refers only to a jacket with brass buttons.

2. It doesn't really matter, but (broad generalization time) two or even one button jackets make you stand out more by forcing you to show more shirt.

3. Never button the bottom button. Double-breasted jackets should always be buttoned. Single-breasted jackets should be worn buttoned when standing and unbuttoned or removed when sitting.

4. Single-breasted and double-breasted refer to how the buttons are arranged. Single-breasted jackets have a single row of buttons, whereas double-breasted jackets have two rows.

5. For the most part, the sport jacket with jeans look is played out. Especially with bootcut jeans. Try to find a one button jacket with interesting details, like satin lapels or something. Make sure the fit is good, or you look like a jerk. Also make sure that the material is sufficiently heavy to stand up to being paired with denim, if you choose to go that route.

I think fit is the most important thing to look for OTR (off the rack). Because you're not likely to be spending the kind of money that gets you a top notch jacket, with full canvassing and high quality wool, you need to shop around to find one that hits you spot on. I'd recommend asking the best dressed MAN in the shop for help, as in my retail experience women don't know sh¡t about fit and neither does your average salesman.

I can't recommend Banana Republic, where I work, and honestly I wouldn't recommend KC either. Karma's jacket looks nice but unless you live in Florida like he does you're not gonna have much use for an unstructured jacket in the fall and winter.

Believe it or not, Target's Merona in-house brand has fitted jackets for super cheap. They WILL fall apart quickly, but if you don't wear them too often they'll last a season, and for $50 who cares? If cheap jackets fit you well, I say get them.