First off, lets understand that one does not need a patent in order to produce and sell a product. You are free to make and sell a product anywhere in the world, so long as you are not infringing someone else’s patent. A patent allows you to stop other people from copying your device.
In a Utility patent, the claims are the legal definition of the protection provided by a patent. Also, a patent is a public document. Therefore, as soon as the patent issues, anyone can get a copy of it and use it as a blueprint to design around it – and that’s fair game, as described on https://azbigmedia.com/business/why-new-inventors-turn-to-inventhelp-for-support/.
Because the Patent Office is required by law to maintain patent applications in absolute secrecy! Therefore, no one can find out when you filed your application or what it actually relates to – unless you tell them, which you never should.
When you have filed your application and put your product on the market, if someone sees it and thinks they might like to copy it, they will see that it is marked “Patent Pending” and they will think, “Gee, if I go to copy that, I may get lots of money tied up in prototypes, tooling, production, inventory, marketing and distribution and, then, just when I am ready to go on the market with it, their patent might issue and I would have to stop – Maybe I’d better copy something else.”
Now, this protection is immediate – because it takes only the length of time needed for them to go through this mental process and decide they had better copy something else. It is broad – because when they look at your device and try to decide what might be patentable about it, for their own protection, they have to give it a broad interpretation. You could use some help from a patenting agency like Invent Help for this.
Finally, it is cheap – because it costs nothing more that the cost of filing the application and paying for amendments to keep it alive. Furthermore, this protection comes during the critical period when you are trying to get your product on the market and establish a market position.