A product option is used for products that come in different variations. Size and color are common examples of product options, but they can also be things like check-boxes or fields for custom text.
Product options are made up of values. A size option would have values like small, medium, and large. For some option types, values are created by the shopper, like custom text fields or file upload fields.
A variant is a particular variation of a product and has specific option values defined — like a small, blue shirt.
You can create a required option for products that need it (like size for clothing). That means the shopper must select a value (like small) before they can add the item to their cart. You can also create non-required options. That means the shopper can select/enter a value, but doesn’t have to. This is good for add-ons or customizations, like engraving.
Stock keeping units, or SKUs, are a code you can assign to products and variants in order to track inventory. With BigCommerce, you can assign SKUs to both the base product and its individual variants.
Rules are a way to change product data — like price, weight, or the image shown — depending on which value-combination or SKU the customer selects for their options.