Informal Summary
We collect information as needed to fulfill our commitments to you, such as delivering purchases you make, and to meet our legal obligations, such as taxes. Except as required by law, we do not share or sell your information for any purpose.
About the web site Differential Geometry
Differential Geometry, operated by freelance mathematician Andrew D. Hwang (“I”), is an online shop that sells original mathematical jewelry and sculpture, original mathematical images printed on wall art, clothing, and other items. The site also hosts a math blog whose aim is to promote appreciation of mathematics and mathematical beauty. Please see the about page for more information.
Below, the terms “we” and “our” refer to the company, Differential Geometry LLC, that I solely own and operate. “Differential Geometry” and “our site” refer to this web site.
Our site is solely devoted to mathematics, mathematical design, and public education and outreach. As matters of principle: We do not collect or retain personal data except as needed to operate as an online shop and blog. We do not obtain revenue by advertising other web sites, or by facilitating third-party analytics sites to track your activities here or elsewhere. We do not use AI for any purpose.
Data we collect and store
When you visit Differential Geometry, we collect your IP address, referrer, and browser type. During your visit we keep track of products you have viewed, which allows us to show you products you have recently viewed.
We use cookies to keep track of cart contents while you are browsing our site. If you create a shop account and log in, we use cookies to keep you logged in.
When you place an order, we require you to provide your name, shipping address, an email address or telephone number, or optionally a shop account username and password, which requests and stores that information. Your shipping address is required so we can calculate taxes and shipping charges, and so we can send your order to you. We collect contact information solely in case we need to communicate with you regarding the status of your order. Your shop account information is used to populate the check-out page with your name and address, and for no other purpose.
When you place an order you must supply payment details, such as a credit card number, in the checkout page. We neither collect nor store these data: Your payment details are securely handled by our payment processor, Stripe. If you have made a prior purchase at a site that uses Stripe, Stripe may auto-fill your payment details at our site when you reach our checkout.
We store information as necessary to fulfill our obligations to you, particularly, to ship orders you place and ensure they arrive in good condition; and for legal requirements, such as our own tax and accounting purposes. We retain order information for at least seven years.
Comments are moderated. Reviews are not moderated. (We are particularly grateful for positive reviews. If you have questions, concerns, or problems with an order from Differential Geometry, please contact us promptly by email before leaving a review; we are happy to work with you!)
If you choose to leave a comment or review, an anonymized string created from your email address (also called a hash) may be provided to the Gravatar service to see if you are using it. Please see the Gravatar service privacy policy (external site) for details. After approval of your comment, your profile picture is visible to the public in the context of your comment. Comments and reviews are subject to being indexed by search engines.
We store and display comments and reviews indefinitely. If for some reason you wish to remove one of your own publicly-visible comments or reviews, we will make a good faith effort to comply, though we reserve the right not to do so.
We maintain a mailing list that is strictly opt-in, to which we send no more than one human-authored message per month.
What we share with others
Your payment details are securely handled directly by Stripe. We do not have access to your payment details, and therefore do not share them.
If you order in-stock items, we share your name and shipping address with the United States Post Office. If you order items we do not stock, we share your name and shipping address with our manufacturing partner, Printify. They in turn share your name and shipping address with a shipping partner so your order can be delivered.
Except as required by law, we do not share your name, email, or other contact information with any third party for any purpose whatsoever.