When we first get a new idea we always want to tell people, We’re excited and we feel really smart, and we just know what we came up with is going to change the world! For the most part telling people in your imitate family and very close friends about your invention is normally pretty safe. What you need to stay away from is telling people just for the sake of telling them, or showing people in ways that it could be classified as disclosure. (ie: a tradeshow, posting it on a forum, or an inventors meetings….)
When you are ready to branch out and start talking about it there are 3 basic levels of protection you want to have in place.
1) An Inventor's note-book. This is a simple thing you can do to document the date of invention. It should be in a bound notebook consecutively numbered. Each page should be signed and dated by two disinterested witnesses stating “witnessed and understood.” The notebooks would be required to be presented to the USPTO to prove the date of invention. Notarized is not necessary but would be a good idea – although generally it’s not practical.
2) A Non Disclosure Agreement: (NDA) this is a document signed between two parties that forms a letter contract stating the receiving party will not disclose what he/she was told about the invention. This is significant because an NDA is enforceable the moment it is signed, and violation of an NDA is a violation of Trade Secret laws. The theory is simple, the person you told could not likely develop your invention without disclosing the details to another party, by doing so they would be in violation of the NDA.
3) A Provisional Patent Application: This is NOT a patent. This is a very basic patent application that is filed with the USPTO establishing the date you invented (or filed) your product/idea. It only has a 12 month life, and then must be replaced with a normal patent application so timing is important.
As you can see from the time you develop an inventor’s notebook you enjoy some level of protection. Each step you take after that is like building the fortress a little higher.
I would say (in my opinion) you are pretty safe telling people in your local circle about your invention once you have a properly documented inventor’s notebook. In most cases with a strong notebook and an NDA you can approach some companies to “test the waters”. But if you’re going to go full force trying to sell your ideas for license I recommend you invest in a PPA before you get too deep into the process.