How the US patent system works.
(1) Trade secret. You don't tell anyone how to make your item (the 11 herbs and spices in a fried chicken batter for example), and thus no one can easilly copy it. If someone does copy it (without illegal activities stealing the design) then they can legally make/sell it.
(2) Direct Disclosure ($10 + stamp), optional. You mail a description of your patentable invention to the USPTO. They store it in a sealed envelope. After 2 years, they destroy it. If an issue arises as to who invented it, the direct disclosure is your undeniable proof. You can do a ghetto version of this by mailing it to yourself and don't open it. Heck for $10 + two stamps, do both. However, this does nothing but identify the date and give you a priority date for further filings (below), you have no other rights.
(3) Provisional patent (~$1000, more if you hire an attorney), optional. This gives you nothing but (a) a date, (b) the legal right to say "patent pending".
(4) Patent ($15,000+ if you hire an attorney). This doesn't even give you the right to sell/make your invention. It allows you the right to DENY others to sell/make the invention in the US.
You can do a patent search (yourself, or pay someone to do it). But a patent search won't find anything in groups #1 or #2. So it isn't foolproof. You might not ever find something and yet it may not be novel.
And you have to do similar things in all other countries (often lumped together in a PCT patent).
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