Do you lose everything when you update to ios 7?

I want to get ios 7, but I'm scared I'll lose my contacts and photos and everything.

I plan on doing it through iphone>settings, not plugging it into itunes.

will i lose my contacts and photos and stuff?

No you won't lose anything nothing at all but you might want to back it up to iCloud

No
But you do loose speed, battery life
And the classic style.
Lots of people hate it( like me )
And the worst part is that you can't go back if you hated it or just do no like it.
It may kill your respect towards apple.
Like it has mine.
That is, there's no going back.

You should not lose anything, HOWEVER… Updating the operating system on any device (phone, tablet, computer, etc) is just about the most drastic change you can make to a device. That being said, I always advise my customers to back up to iTunes before you update *just in case*. Rarely is there a problem, but if something does go wrong (network interruption, corrupt software download, etc) you could lose everything. It doesn't usually take all that long to back up and it could potentially save a ton of heartache.

No, it even saved the apps that were running when i started updating.

I updated without connecting to my computer and I did not lose anything.

I updated from iOS 6 to iOS 7 recently and the only things that got deleted (reset) were my custom network configurations. This is expected since iOS 7 is a totally new operating system.

However, all my games data, pictures, contacts and notes are absolutely safe. None of that got deleted, so you won't lose anything when you update to iOS 7. Just take a backup just in case though. Besides, iOS 7 has far better security.