There are different types of protection. Patents, Design Protection, Copyright, Trademarks and probably some others I've forgotten. Patents are expensive, very expensive and complicated. You would only want to patent something if you knew it was going to make enough money to cover the cost of the patent.
Design Protection can be used to protect the look of an invention, e.g Apple had design protection on the original iMac (the big coloured monitor one), as well as probably some patents on some parts of it.
You probably know about copyright and trademarks.
One thing you can do to help protect your idea is get anyone you talk to about it to sign a confidentiality agreement or a non disclosure agreement, that way you can sue if they talk.
Another thing about patents is you can only patent something that isn't public knowledge, so technically if you tell anyone without getting them to sign one of the above agreements, your idea could be deemed unpatentable.
Sorry if that all sounds a bit naff, I'm no patent attorney I've just been taught a few things during my Engineering degree, most of which I've forgotten.