system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do inventors know if their idea is already patented

I always see these really simple inventions that I KNOW have already been done before, but they seem to make great sales and get away with it. How does someone invent something and get around a patent? Take a gas nozzle holder for example, a device that holds a gas nozzle so you dont have to. Plenty exist, but they all have different designs (I'm assuming so no one sues them for using a patented idea), but how does an inventor know that a patent is already in effect for the invention he came up with? Is there a special search tool for this or something?
gpt
A couple of things:

1. When you make a patent claim, you have to perform a patent search to make sure that no one else has patented what you're proposing.

2. You can infringe on someone else's patent. There's nothing stopping you from doing so. Patents only give the patent owner the right to defend their patent, but the onus is on the patent holder and not the patent office.

3.  Since the onus is on the patent holder to defend his patent, he must constantly search the market to make sure no one is infringing on his patent. If you're a one man shop or a small company, you may not have the legal resources to do this.  Or, if you're small and a larger company infringes on your patent, they can drag out the lawsuit in court for years with their massive legal team, or the small company simply doesn't have enough money to hire the lawyers to fight it in court.