What Happened
You file a patent application. Now what? Examination typically takes 2-4 years in the U.S., involving back-and-forth with an examiner who evaluates whether your invention meets all the legal requirements.
Why It Matters
The examiner will search for prior art and issue an "office action" explaining any rejections. Common rejections: the invention isn't new, it's obvious, the claims are unclear, or the disclosure is inadequate.
You respond to office actions with arguments and/or claim amendments. This back-and-forth can take multiple rounds. Eventually, the examiner either allows the patent or issues a final rejection that you can appeal.
Examination quality varies by technology area and individual examiner. Some art units are more crowded than others. Some examiners are more experienced than others. You can't control these factors, but you can work with them strategically.
Accelerated examination is available for additional fees. Track One prioritized examination can get a patent granted in under a year. For valuable patents, the extra cost may be worth it.
What You Should Know
Be patient. Examination takes time. Rushing usually costs more than it saves.
Respond thoughtfully to office actions. Address the examiner's concerns. Amend claims when necessary. Argue when you have good grounds.
Consider continuation practice. If some claims are allowable but others aren't, you can get the good claims issued and continue prosecuting the rest.
Examination is a negotiation, not a battle. Work with the examiner toward allowance while protecting your core invention.