I am currently reading through a standard Australian patent and in the "Summary" section, I have seen the use of "Preferably", "Advantageously" and "Optionally" used numerous times when beginning almost every paragraph.

Preferably, the web server is controlled by the computer program code to send, via the interface, the property identification data to a property verification server, receive, via the interface, verification of the property identification data.

Advantageously, the application server is adapted to automate the identity verification process of the bidder, the vendor and property so as to substantially reduce manual intervention in the verification process.


Preferably, if acceptance data is not received during the extended auction period, via the interface, representing acceptance of the bid amount by a vendor, then the web server is controlled by the computer program code to close the auction.

Preferably, the configuration data comprises reserve price data representing a reserve price for the property and wherein if the bid amount is greater than the reserve price, then the web server is controlled by the computer program code to record the property as having been sold.

How do these adverbs differ when used in a patent and when should they be used? To a naive person reading those terms loosely (like myself), they all seem to mean "optionally".

  • 2
    I'm voting to close this question as off-topic because it belongs on patents.stackexchange.com Commented Nov 27, 2018 at 14:16
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    @BlueDogRanch many questions that fall into the scope of patents.stackexchange are also within the scope of law.stackexchange—see meta discussion Commented Nov 28, 2018 at 1:57
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    And the question is OK here per this meta Q&A too.
    – feetwet
    Commented Nov 28, 2018 at 20:23
  • As a person with a high reputation on patents.stackexchange.com I'd like to point out that a better answer might have been given on that site than the accepted answer here. Commented Dec 3, 2018 at 7:20
  • Am I still able to re-ask that question on patents.stackexchange.com or would it be marked as a duplicate?
    – ptk
    Commented Dec 3, 2018 at 7:21

2 Answers 2


Preferably and Advantageously are often found in patent applications but current best practice, at least in the U.S., is to avoid those words and many similar words entirely. Today they fall into what is called "patent profanity". The problem is that the rights of a patent owner are supposed to be encapsulated succinctly in the claims. In a back and forth with the examiner the claims presumably get tailored to cover a very specific set of limitations, broad or narrow, as deserved. Imagine the specification says the widget is preferably bigger than a breadbox but the claim is silent on size. Someone making a very small version (covered by the wording of a claim) should be considered as infringing. However, judges have started saying that the "preferably" meant that a larger widget doesn't infringe even though the clear wording of the claim would say it does infringe.

The use of these words has little to do with best mode. Best mode is primarily a U.S. requirement. Most of the rest of the world has no such requirement. In the U.S., the inventor must include the best way they know how to make and use the invention - as of the time of filing. However, there is no need to point out your best mode apart from other versions you might describe. It is currently bad practice to indicate one mode among several presented is your best mode. Again, judges have started saying that if an otherwise infringing product doesn't use the best mode, it doesn't infringe, even though the product clearly falls under the plain wording of a claim. The AIA of 2012 diluted the best mode requirement. It is still required, but the lack of the best mode can no longer be used to invalidate a patent.

"Optionally", is a different story. It is important in drafting a patent application that many versions and variations are described. This can support broader claims. But you do not want any of your many detailed examples of the underlying concept to be seen as "the invention" so almost everything is optional in the specification. Optionally, used in a precise way, can also appear in a claim.


The United States Patent and Trademark Office has a relevant document. As mentioned in the referenced document, the inventor must set forth the best variant of the invention, which would explain using the words "preferably" and "advantageously".

But the inventor doesn't want to let someone evade the patent by building a version that isn't the best, but is still better than what was known before the patent was published. So some features are described as "optional", meaning both the invention with the optional feature, and the invention without the optional feature, are covered by the patent.

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