I don't have a Fitbit, yet, but I plan on getting one when the Charge HR comes out.

What it does depends on the model you get. From the price point and what you've been saying, it sounds like you got the Flex. That gives you sleep and activity tracking.

The Fitbit's claim to fame, especially with the ones you wear all of the time, is its ability to track your entire activity, giving you more accurate feedback on how many calories you burn, regardless of activity level. The watch-style ones (Flex, Force, Charge, Surge) also allow you to track sleep and gauge your quality of sleep by how much you move in the night (the Flex requires you to tell it you're going to bed, while the Force -- when it was available -- and the Charge and Surge automatically detect it). They also give you a silent wake alarm (available on the One, as well), which can be useful for better waking than the garish sound of an audible alarm.

Additionally, you can sync it with dozens of other apps, or possibly your corporate wellness program (if you have one), to do things like earn points or effortlessly keep track of the data your Fitbit tracks. This provides you with a bunch of data that you can use for various purposes.

As for charging, I'd say that for best results, only charge it when you have to, and only for as long as necessary. The batteries are designed to be drained most of the way before charging again, and that way, you're only taking it off for the ~3 or so hours needed for a full charge. Now, that could be best done when you're doing something sedentary, like settling in for the night and watching a movie or something, or even when you're doing something that you can't wear it for -- such as at the beach or pool.

One thing to keep in mind, though -- only the Flex can be worn in the shower. The other models are not that waterproof (for some unknown reason) and need to be removed before such activities (and I think the shower is about the limit for the Flex's waterproofing, but I don't have confirmation of that, so be sure to check your owner's manual or the Fitbit website).

I don't have a tracker. My g/fs got a Garmin and the coolest thing about it, IMO, is the red light thing that comes on if you've been inactive for too long (an hour?).
So she'll get up and do jumping jacks or something to make it go away.
Maybe yours has that feature too? They're all a bit different.

I have the flex and I pretty much use it only for the steps. I've had it for a year now but haven't been consistently wearing it. I wore it at bedtime once and was surprised to see my horrible sleep pattern. Have fun with yours and use it to its full potential!

Hey I just got a fitbit charge and still trying to figure it all out...

I'd love to have some friends on there but I haven't mastered that yet either.
Basically, I just marvel at my steps at this point...lol.

I have a Charge and I love it! It doesn't feel bulky once I got used to it. It really helps me keep physical activity at the front of my mind.

I have a fitbit one, and use it to have contests with my friends. The app on the phone allows you to see who has walked the most in the past 7 days, which pushes me to try to walk more. Also I sync it with mfp and try to ensure that I always have earned a few more exercise calories with it.