Patent questions,
plain answers.

A patent is a legal right granted by the government that lets an inventor exclude others from making, using, or selling their invention for a limited time — typically 20 years from the filing date. In exchange, the inventor publicly discloses exactly how the invention works. It's a deal: you teach the world your secret, and the government gives you a temporary monopoly.

Only what's written in the claims — the numbered paragraphs at the end of every patent. The abstract, drawings, and description exist to explain the invention, but they have no legal force. If a competitor's product doesn't match every element of at least one claim, there's no infringement. This is why 'what a patent doesn't cover' is just as important as what it does.

Utility patents (the most common kind) last 20 years from the application filing date, provided maintenance fees are paid at 3.5, 7.5, and 11.5 years. Design patents last 15 years from grant (no maintenance fees). After expiration, anyone can freely use the invention — which is why generic drugs, open-source designs, and expired tech become available to the public.

Patents protect inventions and functional processes (20 years, expires). Trademarks protect brand identifiers — names, logos, slogans — as long as they're in use (potentially forever). Copyrights protect creative expression — writing, music, art, software code — automatically at creation, for the author's life plus 70 years. A smartphone might involve all three: patents on the hardware, trademarks on the brand, and copyright on the operating system code.

Yes. Once a patent expires, the invention enters the public domain and anyone can freely use, make, or sell it. This is exactly why generic pharmaceuticals exist — the active compound's patent has expired. Aspirin, the zipper, nylon, the telephone — all expired patents that the world now uses freely.

Prior art is any evidence that an invention was already publicly known before the patent application was filed. This includes earlier patents, academic papers, products already on the market, or even a YouTube video. If prior art exists that anticipates every element of a claim, that claim is invalid. Searching prior art is the core of patent litigation — and why patent examiners spend most of their time doing prior art searches.

Claims are the legal boundaries of a patent — think of them like a property line drawn in words. Each claim is a single sentence (however long) that defines one version of the invention. Independent claims stand alone. Dependent claims add narrower limitations to an earlier claim. To infringe a patent, a product or process must match every element of at least one claim. Change one element and you may fall outside the claim.

An independent claim defines the invention on its own — it contains all the elements needed to stand alone. A dependent claim references and narrows a previous claim by adding more specific limitations. Dependent claims are narrower in scope but harder to invalidate, since they require proving all elements of the parent claim plus the additional limitation are in the prior art.

No — you can file 'pro se' (self-represented) at the USPTO. However, claim drafting is highly technical and consequential: poorly written claims are either too narrow (easy to design around) or too broad (easy to invalidate). Most inventors who self-file end up with weak protection. A registered patent attorney or agent is worth the cost for anything commercially significant.

No. US patents only provide protection within the United States. For international protection, inventors use the PCT (Patent Cooperation Treaty) process, which lets you file one international application and then enter national phases in up to 150+ countries. Each country grants its own patent independently — there is no single 'world patent.'

A provisional application is a lower-cost, informal filing that establishes a priority date without starting the 20-year clock. You have 12 months to file a full non-provisional application claiming that priority date. Provisionals let you say 'patent pending,' test the market, and refine your claims — but they never become patents on their own.

Search USPTO's patent database (patents.google.com is often more usable), the European Patent Office's Espacenet, or Google Patents. Search by keywords, inventor name, or assignee. Remember: a patent only blocks use during its term — if it's expired, you're free. PatentBrief explains landmark patents in plain English, which is a good starting point for understanding a technology space.