Terminology
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Products
    A product is a basic entity that can be bought. You can think of it as a ticket type, but it can be more things than just a ticket, it can also be a piece of merchandise, a parking slot, etc.
    You might find some places where they are called "items" instead, but we're trying to get rid of that.

Product categories
    Products can be sorted into categories. Each product can only be in one category. Category are mostly used for grouping related products together to make your event page easier to read for buyers. However, we'll need categories as well to set up some of the structures outlined below.

Product variations
    During creation of a product, you can decide that your product should have multiple variations. Variations of a product can differ in price, description, and availability, but are otherwise the same. You could use this e.g. for differentiating between a regular ticket and a discounted ticket for students, or when selling merchandise to differentiate the different sizes of a t-shirt.

Product add-ons
    Add-ons are products that are sold together with another product (which we will call the base product in this case). For example, you could have a base product "Conference ticket" and then define multiple workshops that can be chosen as an add-on.

Product bundles
    Bundles work very similarly to add-ons, but are different in the way that they are always automatically included with the base product and cannot be optional. In contrast to add-on products, the same product can be included multiple times in a bundle.

Quotas
    Quotas define the availability of products. A quota has a size (i.e. the number of products in the inventory) and is mapped to one or multiple products or variations.

Questions
    Questions are user-defined form fields that buyers will need to fill out when purchasing a product.
